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8/14/2019 Microbiology Lecture - Immunology
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I MMUNOLOGY
I MMUNOLOGY
Mark Michael J. Cuevas,
an introduction
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Resistance
The ability to ward off diseasethrough our defenses
Immunity
Ability of the body to specificallycounteract foreign organisms orsubstances called antigens
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Immune System
Functional system that recognizes foreignmolecules and acts to inactivate or destroy it
Composed of many interdependent cell types thatcollectively protect the body from bacterial,
parasitic, fungal, viral infections and from thegrowth of tumor cells
Can engulf bacteria, kill parasites or tumor cells orkill viral-infected cells
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BONE MARROW
Organs of the Immune System
Produces B-cells, natural killer cells,granulocytes and immature thymocytes,
in addition to RBCs and platelets
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THYMUS
Organs of the Immune System
Produces mature T-Cells, which are thenreleased into the bloodstream
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SPLEEN
Organs of the Immune System
Immunologic filter of the blood
Made up of B-cells, T-cells, macrophages, dendriticcells, natural killer cells and RBC
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LYMPH NODES
Organs of the Immune System
Immunologic filter for the bodily fluidknown as LYMPH
They are connected by lymph channelsand capillaries, which remove foreignmaterial from the lymph before it enters
the bloodstream
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I MMUNITY
Ability of the host to defend against a
particular infectious agentIt results from the production ofspecialized lymphocytes and antibodies
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AcquiredImmunity
Immunity that results from the active
production or receipt of antibodies duringones lifetime
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Types of acquired immunity
NATURALLYACQUIREDIMMUNITY
ARTIFICIALLYACQUIREDIMMUNITY
NATURALLYACTIVE
ACQUIRED
IMMUNITY
NATURALLYPASSIVE
ACQUIRED
IMMUNITY
ARTIFICIALLYACTIVE
ACQUIREDIMMUNITY
ARTIFICIALLYPASSIVE
ACQUIREDIMMUNITY
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1. The baby has received a BCG vaccine at thetime of its birth
2. A 5-year old child contracted chickenpox andthe disease did not recur thereafter
3. The community nurse gave OPV to a 6-monthold infant
4. The mother breastfeeds her newly born childevery four hours
5. The doctor administered Rabies ImmuneGlobulin to a 17-year old male who was
admitted in the ER due to dog bite
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VACCINES
A suspension of organisms or fractions of organismsthat is used to induce immunity
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Types of vaccines
ATTENUATEDVaccine
INACTIVATED
VaccineCONJUGATEVaccine
Killed pathogens
Bacterialcapsular antigen
Weakened oravirulent
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Types of vaccines
SUBUNIT Vaccine
TOXOID Vaccine From ExotoxininactivatedAntigenic
portions of apathogen
DNA VaccinePlasmidsinjected into
skin/muscletissue
AUTOGENOUS
Vaccine
Isolated bacteriainjected to
induce more
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Antigenic variation
A change in surface antigens of some viruses
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Humoral Immunity
Duality of the immune system
Also termed as ANTIBODY-MEDIATEDIMMUNITY
Involves the production of ANTIBODIES
B-Cells are responsible for the production ofantibodies
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Cell-mediated Immunity
Duality of the immune system
Involves specialized lymphocytes calledT-cells
Most effective against bacteria and viruses located
within phagocytic or infected host cellsAlso an important factor in our defense against cancer
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Humoral Immunity
Nature of antigens
Antigenic Determinants (Epitopes) component of a bacterial cell wall that iscapable of stimulating the production ofantibodies
Haptens small molecules that it is notoften antigenic unless it is attached to acarrier molecule
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Humoral Immunity
Nature of antibodies
Belong to a class of glycoproteins calledImmunoglobulins
Highly specific and only react with only one antigenicdeterminant
Basic structure resembles the letter Y
- 2 identical heavy and light polypeptide chains
- 2 antigen-binding sites
- Fc region
- chains are connected to each other bydisulfide bonds
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Immunoglobulin classes
Only Ig that can cross placental barrier Long-lived and most abundant in serum
Protect against bacteria and viruses, neutralizebacterial toxins and enhance effectiveness ofphagocytic cells
IgG
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Immunoglobulin classes
Found in saliva, tears, seminal fluid,colostrum, breast milk and mucoussecretions of nose, lungs and GIT
Most abundant in the body but short-lived
Prevents attachment, colonization andinvasion of pathogens
Protects infants from GI infections
IgA
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Immunoglobulin classes
Does not cross the placenta
First to appear in response to exposure to anantigen
Bactericidal to gram-negative bacteria
Relatively short-lived
IgM
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Immunoglobulin classes
Produced in response to allergens
Found on the surfaces of basophils and mast cells
IgE
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Immunoglobulin classes
Found in large quantities on the surface of B-cells, some in the blood and lymph
Function is unknown
Act as antigen receptors on the surface of B-cells
IgD
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Blebbing Necrosis
B-cells do not encountera stimulating antigen
Apoptosis(programmedcell death)
Attractsphagocytes
Inflammation
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Cell-mediated Immunity
Chemical messengers
Inhibitory or excitatory
Cytokines /Lymphokines
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Types of cytokines
Stimulates THcells in presence
of antigens
Attracts phagocytes ininflammatory response
Interleukin-1
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Types of cytokines
Proliferation of antigen-stimulated TH
cells
Differentiation of B-cells
Activation of TC cells and NK cells
Interleukin-2
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Types of cytokines
Induces migration ofleukocytes into infected areas
Interleukin-8
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Types of cytokines
Inhibits viral replication
Increases activity of macrophagesagainst microbes and tumor cells
Gamma-Interferon
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Types of cytokines
Cytotoxic to tumor cells
Enhances phagocytic activity
Tumor Necrosis Factor-Beta
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Types of cytokines
Stimulates formation of red andwhite blood cells from stem cells
Granulocyte-MacrophageColony Stimulating Factor
S i li d
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Specializedlymphocytes
Developed from stem cells inthe bone marrow
Precursors migrate and reachmaturity in thymus
Mature cells migrate to variouslymphoid organs
T-Cells
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Types of t-cells
Influence the activity of other
immune system cells
Helper T-Cells
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Types of t-cells
Destroy target cells on contact
May kill cancer cells and cellsof transplanted tissue
Cytotoxic T-Cells
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Types of t-cells
Associated with allergic reactions
DelayedHypersensitivity T-
Cells
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Types of t-cells
Regulate immune response by
turning it off
Suppressor T Cells
Specialized
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Specializedlymphocytes
Found in resting state
Phagocytic cells
Stimulation is primarily byingestion of antigenic materialor by cytokines
More effective
ActivatedMacrophages
Specialized
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Specializedlymphocytes
Capable of destroying other cells
Can also attack large parasites
Are not immunologically specific
Natural Killer Cells
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Bodys Immune Response
1.Discriminatory
2.Specificity
3.Anamnesis
4. Transferability of Living Cells
4 Characteristicsof ImmuneResponse
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Bodys Immune Response
First exposure to antigen
Primary Response
Characteristics:
Long-latent period
Slow rise in blood titer Low peak short plateau
Period of decline as fast as rate of increase
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Bodys Immune Response
Subsequent exposure to antigen
SecondaryResponse
Characteristics:
Short-latent period
Rapid increase of titer Peak of antibodies produced is very high
Extended plateau
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