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Immunology Lecture #2 (1)

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    53

    2

    Basic Concepts and Components of the

    immune system

    Amin Al-Baik

    Ziad Al-Nasser

    Monday, 4/7/2011

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    Lecture # 2, chapter 2

    Date: Monday, 4/7/2011

    Done by: Amin Al-Baik

    Basic Concepts and Components of the immune system

    Review for the first lecture ((Ch#1 mainly))

    Everybody got the Idea about Immunology course, and yesterday we have startedtalking about some of the concepts and terminology that we have been using in the

    science of Immunology.

    We talked about Louis Pasteur (who created the first vaccine for rabies andanthrax)and the vaccination against rabies which give you thing that doesnt kil l

    you, but makes you stronger.

    and we talked aboutEdward Jenner who is considered as the father ofImmunology for his discovery of the vaccination against the smallpox; where he

    noticed that shepherds, who got cowpox, they didnt get the smallpox, so he took

    from the vesicles of cowpox (lesion has a fluid), he took from that fluid and injected

    that to people, they expected to be getting the smallpox, but then they wereprotected.

    I told you that vaccination starts with vaca which means (cows) in the Latinlanguage, so the terminology came from a cowpox vaccination byEdward Jenner,

    and we started talking about the main divisions of our immune system and its

    significance in defense; the nonspecific one = the innate , and the specific one = the

    adaptive .

    1

    http://en.wikipedia.org/wiki/Vaccinehttp://en.wikipedia.org/wiki/Rabieshttp://en.wikipedia.org/wiki/Anthraxhttp://bword//!!09HMK27M2P,Jenner,%20Edward/http://bword//!!09HMK27M2P,Jenner,%20Edward/http://bword//!!09HMK27M2P,Jenner,%20Edward/http://bword//!!09HMK27M2P,Jenner,%20Edward/http://bword//!!09HMK27M2P,Jenner,%20Edward/http://bword//!!09HMK27M2P,Jenner,%20Edward/http://bword//!!09HMK27M2P,Jenner,%20Edward/http://en.wikipedia.org/wiki/Anthraxhttp://en.wikipedia.org/wiki/Rabieshttp://en.wikipedia.org/wiki/Vaccine
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    And we said that:

    1- The nonspecific (innate) is much faster, it is the one we are born with, (E.g physicalbarriers and mucus membranes), they make the bulk of the first line of defense. We

    have the second line of defense, (e.g. serum and its constituents, WBC other than T

    & b lymphocytes i.e. WBC which perform phagocytosis, and the complement

    system), about cells (e.g. neutrophils, phagocytic cells, natural killer cells,

    macrophages), all of them are nonspecific, and those cells can produce cytokines

    which are components trigger the cells; they interact with each other, some are

    upregulator (enhance) and some are downregulator (suppress).

    2- Then we said on the other side about the specific of immune response, where wetalked about specificity, and we talked about memory at the same time, and we

    talked about antigen-recognition moleculesreceptors and antigenic epitopes that

    have to fit into those receptors, and we said that we were born with sets of

    receptors on the surface of those T and B-cells, if those are there then we are

    responders, and if they arent there then we are not responders.

    So when we talk about T cells, B cells, major histocompatibility complex (MHC),

    antibodies, memory cells, receptors and antigenic determinants (epitopes),

    We talk about adaptive immune response

    Then we talk about adaptive immune response, and we said also vaccination is theone of the successes of our immune system, and we will talk in details about it, andits program, and we will talk about transplantation, we have sometimes to

    transplant a kidney or a cornea or even blood! , blood transfusion is considered as a

    type of transplantation, and how we are going to keep that into perform the

    function, so sometimes we need to suppress the immune system in order for our

    body to accept that particular graft (the part which is transplanted), and also we

    said that it is so important for you to understand the molecular interactions,

    molecular reactions, biochemical pathways, which will take place, why?? Because if

    any defect happened during that pathway, then we are going to have immune2

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    deficiency, or we can manipulate those by drugs to suppress the immune system. So

    we said sometimes in hereditary diseases, the enzyme could be defective, and loss

    enzymes expressed by genes, so in order to replace those genes we could do gene

    therapy and we will talk about it later..

    and some of the failureof the immune system other than immune suppression ,lack of these cells that we talked about, enzymes , genes and so on, sometimes our

    immune system could go over reactive and this result in hypersensitivity or

    Allergies; they could kill people; so we have to identify that, also we said one of the

    major specific function of the adaptive immune system is to recognize self from

    nonself, and we said this occurs in the major lymphoid organs, in the thymus gland,

    and in the bone marrow, any defect in this normal process, then we will have

    autoimmune disease , and these autoimmune diseases (e.g. systemic lupus

    erythematosus, rheumatoid arthritis), they could lead to death, we will see how to

    treat those later on.

    For example look to this patient who hashepatitis B infection, it is chronic hepatitis

    caused by Hepatitis B virus, and these patients

    have jaundice. (Figure #1)

    look to the *sclera here(figure #1), you can see

    yellowish discoloration of the sclera. So, one of

    the causes of jaundice is hepatitis B, and classical

    causes of hepatitis , hepatitis A , hepatitis B ,

    hepatitis C.

    Hepatitis C is the mostserious one, it could infect the health care workers , and killsa lot of people all over the world, in USA it kills more than one MILLION every year,

    they die by hepatitis.

    *Sclera:

    is a white fibrous membrane

    which covers the eye.

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    We need to have precautions and vaccination, because some of the health care

    workers could be infected when they are dealing with the patient with hepatitis,

    and everybody who comes to the hospital should be vaccinated with Hepatitis B,

    also hepatitis B could lead to liver failure , chronic hepatitis, hepatocellular

    carcinoma and death, this disease is sexually transmitted disease. Also we talked

    about influenza, and that its viruses are so evasive (they have ability to change their

    antigenic structure), so we could be infected with one of them frequently, and there

    is another example for the evasive viruses: Herpes Viruses which suppresses the

    production of major histocompatibility antigens, which are the major role in

    defense. However, Influenza could disguise with normal tissue covering itself with

    mucus plug, so we should know all the pathogens, their evasive mechanism and our

    counter measures to get rid of them. About influenza we told you that we use

    upgraded vaccine every year.

    This is the sneezing and cough, they are the wayby which we get rid of respiratory particles,

    which next go into the air, floor, chair, and

    hands, then you shake hands with someone,

    and then pathogens will be transmitted to him

    and so on, this is the droplet of transmission.

    The most two important features of adaptive immune system are: specificityand memory. For example how we can modify our immune system in order to

    increase the number of memory cells; then will be protected against these

    organisms, and the classical example is the use of hepatitis B vaccination, we

    give three doses (sometimes we give two doses), between the first and the

    second dose there is a period of around one to two months, and the time

    between the second and the third dose is four to six months, so we give morethan one dose, in order to increase number of memory cells.

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    the primary immune response is the response comes after first dose untilsecond dose, in this period the antigen will be recognized (recognitive phase),

    the antigens bind through the receptors, the receptors through the clonal

    selection theory, you must have cells that will develop into clones, the clones

    will differentiate and proliferate increasing in number, and memory cells will

    develop and immunoglobulins.

    After second dose (secondary immune response), there is an increase in

    immune response, and the period for the immune response to take place will

    be much shorter i.e. it is faster, because memory cells have already developed.

    And the type of the immunoglobulins that will develop is different, they are

    with high affinity binding, so strong, neutralizing antibodies.

    After third dose, the response will be much much higher, we will have huge

    amount of immunoglobulins in few months.

    The different between the primary and secondary immune response is that the

    primary takes longer period of time ends up with development of memory

    cells, but the secondary, the type of immunoglobulin of which is much better

    than the primary, they last longer, and the binding of them is so strong (high

    affinity), and we call the secondary immune response another name which is

    anamnesia which is in contrast to amnesia, anamnesia is the reaction that

    remembers, so develops memory cells.

    this patient has renal failure (figure 1.8, p5, ch1) , and you know when kidneysfail, there is no way to recover it except to do kidney transplantation, and

    kidney transplantation needs donor to give and the patient which is recipient,

    and we must have tissue match, in order the recipient to accept the donors

    kidney.

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    and the role of histocompatibility antigens , each of us has sets of haplotype, Iinherit half of genes from my father and half from my mother, this is called

    dominant type of expression , and those genes are the ones that stimulate the

    immune response and genes, and antigens which will respond immunologically

    , so if we have the same setup genes , that means same antigens = no immune

    response = graft will be accepted and vice versa, until now there is no way to

    reach 100% match, so we are going to do suppression of the immune response

    (by using immune suppressor drugs), so patient will accept graft, there is a lot

    of organs to make transplantation , e.g. cornea transplantation is the most

    successful types of transplantation .

    There are some similarities anddifferences between adaptive and

    innate immune response :

    - Innate is non-specific andadaptive is very specific.

    - Innate is fast (minutes), whileadaptive needs time to develop so

    it is slow (days).

    - Innate is without memory, unlike adaptive which is with memory.- The innate include natural killer phagocytes and secreted molecules; the

    adaptive has lymphocytes (B & T cells) and also secreted molecules.

    - There are few pattern-recognition molecules in the innate (they develop aspattern for group of antigens) like a polysaccharide, and there are many

    Antigen-recognition molecules in the adaptive.

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    Chapter #2: Basic concepts and components of the immune system

    About interactions between twoimmune systems look at the figurehere : > >

    - You require Antigen-presenting cell(APC) for the specific immune

    response or what we call thymus

    dependant antigens. However, About APC E.g. dendritic cells, interdigitating

    cells, B cells itself, and Macrophages could detect the antigens, process it andthen present it with class 1 and class 2 of MHC.

    - This process (presenting & Processing antigens) is required for the B and Tlymphocytes to be activated, and requires complement chemotaxis and

    phagocytic process I.e. we will see that 1st line, 2nd line ,3rd line of defense and

    primary immune response all of those mechanisms will help each other in

    order to make the defense.

    - For example , if you get a bacterial infection , then those bacteria will be takenby the APC , it is processed and then presented to T and B cells, and you know

    we have different types of T cells , and the most important one is T helper

    (the main (or the orchestrating) cell in our immune system).

    - CD4 cells, is the T cell which has CD4+ antigen. Note: Orchestra means:band composed of musicians of many different

    instruments. and we said that about T helper cell coz it produces cytokines

    which manipulate, activate, suppress, and regulate the rest of other T cells

    or B cells, the B cell without the cytokines which produced by T helper cell

    will not produce immunoglobulin as much as when the cytokines is present,

    so the importance of the APC is for activation of T and B cells, and

    production of immunoglobulin.

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    - We talked that, Immunoglobulins when they develop, this is what we callhumoralimmune response, and this is required for neutralizing viruses,

    toxins and pass through the placenta... etc.

    - sometimes we require to kill in cell , and this is what we call cell mediatedimmune response , if you have a viral infection for example , and the target

    cell is infected , and the virus is inside the cell , so we need to activate T cells to

    kill that virally infected cell.

    - Part of cell-mediated immunity is done by adaptive immune response, and thecells which are involved we call it T cytotoxic cells, and the other part by the

    innate we call them natural killer cells. The mechanism of the killing in both is

    the same , but the difference comprise the recognition of the particles , i.e. the

    T cytotoxic cells recognize particles by the receptors that present on the

    surface of it , while natural killer cells do that by different mechanisms like

    antibodies that are going to bind receptors.

    - We will talk to you about the Major histocompatibility antigens and its majorrole, and the expression of those antigens on the surface of those cells will

    determine whether T cytotoxic cells will take an action and kill or the natural

    killer cells will do that, we can see that we have so many alternatives for

    getting rid of invading micro-organisms.

    - Again, there are similarities and differences between the innate and the adaptiveimmune response:

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    Innate immune response:-

    The response time is fast. The pathogen (non-self) recognition mechanisms are few. There is no memory. There is no improvement, unlike the adaptive.Adaptive immune response:-

    The response time is slow. The pathogen (non-self) recognition mechanisms are so many. It has memory. It has improvement by changing of the type of immunoglobulin that they will develop

    and this development will change even a binding affinity.

    Innate immune response

    1. Phagocytosis and MBL(mannan binding lectin) of the C(complement) system whichis non specific, we will tell you more about that.

    2. cells that are involved in non-specific :-a)Neutrophils : those are the major cells that are involved in Phagocytosis, they are

    developed on daily basis , they have short half life ,they are present in huge number,

    neutrophils live less than 24 hours, and then it will expire, they are called by process

    called Chemotaxis, and chemotaxis require cytokines to be expressed or secreted, sothey (cytokines) will call those cells (neutrophils) to come in the area, mainly they are

    called upon when I have bacterial type of infection, so when I see lots of neutrophils;

    I know this is what we called pyogenic infection, when the process is finished they

    turn to pus cells, they get expired by the act , and they have so many killing

    mechanisms we will talk about them later.

    b) Macrophages: they differ from neutrophils, Macrophages are larger, they last longer,

    but they are not high efficient; coz their number is less, they can phagocyte once,

    twice, and third. They dont expire by the act, unlike the neutrophils.c) Naturalkiller cells (NK): non- specific cells, they kill virally-infected cells and tumor

    cells, and they are the main surveillance cells of our body, they keep circulating in

    our body, I will tell u more how they kill later.

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    Morphologically, when we look to them under the microscope they look like

    lymphocytes but the difference between NK cells and the lymphocytes that NK dont

    have specific receptors against Antigens. In fact they are used to be large granular

    lymphocytes, but in reality they are not granular: they are not lymphocytes, they look

    like lymphocytes and they develop from the progenitor cell of lymphocytes.

    Mechanism of killing: the initiation is difference, but the outcome is the same, both ofthem produce substances we call them cytotoxins and cytolysins that they will kill

    virally infected cell, they kill the virally infected cell or the tumor cell by convincing

    the cell to commit suicide we call that apoptosis.

    3. Interferon: one of the most important cytokines produced from many cells. AlphaInterferon (), beta Interferon () and gammaInterferon (); gamma type is

    produced from T-helper cell. Alpha from WBC, beta from tissue, and the interferons

    provide protection of cells mainly against viral infection .they are excreted from cells

    which are infected with viruses mainly and provide protection to others against viral

    infection, I.e. the outcome is the destruction of the messenger RNA of the viruses.

    So, remember that the Innate and the Adaptive immune response are interconnected

    through the cytokines, they perform dual function, they help each other and they

    work as a team.

    Adaptive immune response

    The adaptive Is specific , distinguishes self from non-self , it has Diversity of antigenrecognition molecules and so many genes that are produced so, this is why your

    new response is different from mine ; it depends on the gene that you have inherited

    from your parents and gene that I have inherited from my parents which is going to

    determine the receptors on the surface of the lymphocytes so, if you have the same

    receptors as the ones I do, then you will react the same, if you have more than me,

    you will react better.

    More genes you have inherited from your parents more lymphocyte cell surface

    receptor more efficient reaction with antigen

    The importance of diversity to you is to have more genes more receptorsmoredifferent cells than mine, to encounter all the different pathogens that we could be

    exposed.- Which determines the diversity of genes is the inheritance of your parents.

    the ones they have what we call Intersanguineous marriages ; if my

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    mother and father they are so related to each

    other, then the types of genes that Im going

    to get from my father and mother they are

    going to be the same .they arent going to be

    diverse as such compared if may mother and

    father are not related to each other, then the polymorphism and the diversity, they

    are going to be enormous So, I will have better chance of responding to pathogens

    and foreign cells than the Intersanguineous marriages.

    - Then always we said : (()) *We will keep talking about that when we cometo the genetics of immunoglobulin and

    its diversity B-cell, T-cell receptor diversity.

    Somatic mutation: the change that occurs at the binding site of that immunoglobulinand what we call a better fit of an immunoglobulin compared to a weak fit. The

    nature of immunoglobulin will develop, so the somatic hypermutation occurs in the

    secondary immune responsei.e. after primary immune response; cuz primaryresponse is just to recognize, and the mutation in secondary is for make the binding

    sites better fit.

    Receptors prior exposure to antigens: this is what I want you remember we haveborn with receptors on cells, those receptors do not develop when antigens enter

    our body. I want u to remember this important information: receptors they arealready there, they are determined with set of genes that we inherit from our

    parents, so when we are exposed to antigen; if you have the cells then interact, if you

    do not have, they will not interact.

    Receptors of antigen are determined by genes that we have inherited from our

    parents, and arent determined by antigen that is going to enter our bodies"

    Clonal expansion:will take place. This what we call clonal selection theory, we mean by clonal selection

    theory that We are born with cells which have already receptors there, and the clone

    that is selected is going to be activated, and proliferated.

    Self receptors must be deleted or inactivated: why?? All the progenitor cells thatthey come from the bone marrow, they go to the thymes glandin order to develop

    into what we call T-cells ( T from thymes) or in the bone marrow into B-cell (B frombone marrow), the main function to those progenitor cell to do into thymes gland ( T-

    cell) or in the bone marrow (B-cell)is to get rid of the self reactive cells ; the cells that

    are supposed to react against self antigen should be deleted . If this process fail for

    *)) ((--

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    one reason or another we are going

    to have an autoimmune phenomena.

    I will tell u more about this autoimmune

    diseases, and how they develop and

    all the theories and what I mean by

    tolerance, and how the tolerance is

    broken out.

    This is what I was talking about, you have

    so many different B-cells we are born

    with; with much different

    specificities, i.e. in one cell we have

    one type of specificity.

    When we are exposed to non-self, so

    non-self it has to find its match , if the

    match is there, it is going to bind, this

    is going to expand, this clone will

    develop, proliferate and immune

    response going to take place.

    If non-self doesnt find the match, no immune response going to take place, and Im

    considered as an immune compromised.

    These are the antigen- recognition molecules and the specificity that is involved inadaptive immune response and in the innate immune response.

    innate immune response: we dont have many genes that are involved, thats whywe dont have the specificity of the adaptive or specific immune response .

    Ancestralgenemodern gene pattern recognition molecule

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    So, you can see on the surface of the macrophage a receptor, this receptor for so many

    antigens at the same time, this what we call it pattern recognition molecule .for

    example; antigen recognition molecule will recognize the lipopolysaccharides in all

    gramvebacteria .

    While in adaptive immune response, so many genes are involved that we inherit fromour parents , and those will be selected one at the type its so interesting, ones that

    are selected one at the type will end up on the surface of those cells for the clonal

    selection theory which we have talked about.

    Ancestral genesgene duplicationmodern genespecializationantigen

    recognition molecule.

    major histocompatibility complex antigen : that will give u major histocompatibility

    proteins, when we talk about major histocompatibility, we talk about class and class

    ; class :locus a , b and c ,and we have two allelic forms, that are present on every

    cell in our body: ones come from father and the 2 nd come from mother so, if the

    mother and father are related to each other , for example ; a1 from father and

    mother has a1 as well we end up with a1, but if mother and father they are not related

    a1 and a2 then I will have a1 and a2 at the same time .

    A1 will look different than a2, so here the chance that Im going to have to be exposed

    to a varietyofantigenic determinants will be much higher. So, these are we call

    specificity that comes by inheritance.

    again locus a ,b ,and c for class and d, r ,p and q for class and we require two; one

    from the father and one from the mother, so will end up with 6 minimum ; when

    mother and father are related to each other and have the same set of genes , and

    maximum 12, if the mother and father are different completely I will be more diverse.

    The mother gives 6 and the father gives six also, so we will have 12 if there arent any

    similarities (considered as maximum), if they are related, then there will be some

    similarities, and this will make it less than 12, i.e. may be 10, 8, and 6 as minimum

    The same thing in the T- cell receptors and Immunoglobulins, I will tell you what arethe type of those genes that is going to make which types of proteins of

    immunoglobulin or the T or B cell receptors, so genes will determine specificity, if

    that gene is selected, that protein will appear on the surface of cell and that type of

    immunoglobulin is going to be excreted.

    The T-cell receptors on T-cells and Immunoglobulins of B-cells, all of them are calledAntigen recognition molecules. There is single antigenic determinant or epitope

    which can be recognized by one of those T-cells, B-cells or immunoglobulin as we are

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    going to see. This in adaptive while in

    innate there is pattern recognition

    molecule for the whole group of

    bacteria, and so on.

    This is how self reaction could fail: ifyou have B-cells for example, by one of

    the mechanisms manage to escape the

    deletion in the bone marrow or the T-

    cells in the thymes gland and they

    managed as you can see here with

    many different specificities depends on

    the antigenic determinant that we

    have, and if we have self antigen could

    react here as you can see with the B-cells, and the B-cells are going to react and

    produce immunoglobulins and those immunoglobulin will attack our own tissue

    ,complement could be activated and that tissue is going to be destroyed. They think

    this is foe, and they are going to have autoimmune disease, this could happen, it is

    this unusual; it is a disease; I will tell you how this will develop and how we prevent

    that from taking place.

    The component of our immune system

    Very important points regarding the adaptive immune system:-

    1. Specificity: I mean by that the antigenic determinants and receptors.2. Diversity: so many types, so many receptors, so many antigenic determinants that

    we have talked about, immunoglobulins and MHC antigens.

    3. Memory: second time is not like the first time.We are talking about cells specific and non-specific ,

    1. Specific cells:-are T cell and B-cell.2. Non- specific: - we are talking about macrophages, neutrophils, eosinophils,

    basophils, mast cells and NK cells, each one has a deferent function.

    And we talked about soluble molecules like cytokines, for example for cytokines:

    interleukin and interferon, they are soluble mediator that the cells utilize and interact

    with each other, all of those cells and their function should be know all the cells I

    have mentioned that they play a role in our immune defense.

    Cell mediated immunity: - involvement of virally infected cell and tumor cell

    E.g. T-cytotoxic and NK cells.

    Humoral immune response antibody mediated cell:-

    It is the immune response that uses immunoglobulins for defense, antibodies, B-celland Plasma cell that are involved. And remember here the notion of antigen

    presenting cells ~APC~ and their function, and this is mainly for thymes dependent

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    antigens, the function of T-helper cells which will never accept to participate in the

    game unless the antigen is presented to her by APC.

    You should know what these APC are.

    APC:

    E.g. 1)

    interd

    igitati

    ng cells, 2) macrophages 3) and B-cell itself has dual function.

    And remember secondary immuneresponse and primary immuneresponse that we

    have talked about, and why we use what we call it boosterdose; dose two and dose

    three , sometimes we give more than that, for example in poliowe give 5 doses at 2

    months ,4 months ,6 months , one in half year pre-school. The main reason why we

    give booster dose is to increase the number of memory cells and to have a better fit,

    andbetter functioning immunoglobulin.

    If we give booster doses continuously, Our immune system will figure out that this is

    not needed and instead of having and activation of immune response, our immune

    system through the signals - we will talk about that later in the regulation of immune

    response -will give a suppression signals to T-cells to stop doing that.

    We can do that if I want to suppress the immune system. do you know the

    hyposensitization which is used to treatment of allergies and hypersensitivities ??

    what do we do in order to treat allergy if we are allergic to olive pollens ?. the idea is

    not to be expose to the pollens of olives , but we cant do that if the patient live in

    the area with a lot of pollens in the air. So, how Im going to get rid that permanently

    once and for all; I will be exposed to the antigen of the olives pollen continuously so,

    here patients body will realize that this is not needed so, start to produce

    mechanism will tell u more that At the end, every time he will be exposed to olive

    pollens, the suppression of the immune response is going to take place. This is the

    idea why you should not give continuously booster doses.

    This was studied how many booster doses I should be given in order to

    have ultimate immune response that is going to protect me forever.

    Cell meditated immunity: T cells which eliminate intracellular pathogens!

    Humoral response: B cells (antibodies) which eliminate extracellular pathogens.

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    Cells of the Immune System

    1. Innate :-Neutrophils 66%:-

    They have granulocytes which have granules,

    and these granules have enzymes like:

    myloperoxidasis, I will tell you more about

    those and how they get activated and how

    they produce cytocidal, molecules. And

    how they kill the bacteria and phagocyte.

    Eosinophils 4% :-

    We will see where eosinophils will be

    produced, and which type of infections in

    which we see eosinophils. Parasitic type

    of infection and in allergies .

    You know the percentage of eosinophils is 4%,

    so if I see eosinophils go up to around 40%

    then I know that I could be infected withparasite, or I could have allergy. The

    granules that are produced by eosinophils are so important for neutralization of

    vaso-active amines that are produced in allergies.

    Macrophages:-

    They are considered as Phagocyticcells and antigen presentingcells.

    and Macrophages differ from neutrophils,

    i. They dont get expired by Act.ii. They can phagocytose once , twice , third, in fact we see those sometimes when we

    have immune complexes, if I have antigen antibody reactions, those immune

    complexes could develop and precipitate in tissues , if this happened the

    macrophages come and try to phagocytose immune complexes .If they are free in

    serum, macrophages could phagocytose immune complexes and clear our bodies

    from them, but if immune complexes bind into the tissues like basement membrane

    of the kidney, so the macrophages come and try to phagocytose those and they

    couldnt, bcz they are so adherent to the basement membrane of the kidney, what

    the macrophages will do is to release vaso-active amines over the basement

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    membrane, and they cause damage to the basement membrane, we called those

    frustrated macrophages.

    And this is the damage that occurs to the

    basement membrane, the joints and the

    others; this is bcz of the phagocytes .for

    example ; one smoker who have chronic

    bronchitis why ?. bcz the carbon molecules

    stimulate macrophages ,these

    macrophages release their enzymes into

    the cells , they damage the cilia , and

    stimulate the mucus cells to produce

    mucus and coughing and end up chronic

    obstructive lung disease.

    Mast cells:-

    They are involved also in hypersensitivity types of reaction.

    Natural killer (NK) cell:-

    It is looks like a lymphocyte but they are large,

    and have larger granular than lymphocytes,

    and the NK cells involved in virally infected

    cells tumor cells as well.

    2. Adaptive :-T- helper cell or T cytotoxic all of them look the

    same, and there are plasma cells that are

    differentiated from B-cells but if u look at the

    fig. down at these type of cells and what is

    the outcome of their activation; if you have B-

    cell and T-cell, morphologically they look the

    same, so how we differentiate between B-celland T-cell if they are looking the same?? Based

    on the antigenic marker that presents on

    their surfaces:

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    B-cell: - have immunoglobulin on their surface IgM.

    T-cell: - have CD4+ and CD8+ .

    B-cell can be activated to change into plasma cell and then immunoglobulin will develop

    .while T-cell if it is T-helper as you can see T-helper has CD4+ when gets activated

    produces cytokines, thats why it is orchestrator cell .and if you look into the surfaceof the T-helper, there is one type of a receptor one shape wedont see 2 shapes in

    one cell, this is the clonal selection theory.

    And the T- cytotoxic cells has the same thing they have CD8+ as surface marker and I will

    stop here.

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