LPN Basic Immune System Overview

The Immune System, Diseases and Treatments

Introduction for LPN Review Course

December 27th, 2010

Immunology

• Immunology: the study of how our bodies defend themselves

• Immunity: The ability of our bodies to protect themselves from infection

• The Immune System: all of the tissues, cells and molecules used to mount an immune response

Purpose of the Immune System• Protects your body from things that

should not be inside of it –Any “non-self” cells

–Bacteria–Viruses–Fungus –Parasites –Cancer (cells gone “bad”)

The lymph system & associated

organsDefinition: Immune (Lymphatic) System -- The immune or lymphatic system consists of a complex network of specialized cells and organs designed to protect and defend the body against attacks by "foreign" invaders such as bacteria and viruses

Immune System Components

• The immune system consists of:– specific cells (lymphocytes, macrophages, etc.)– lymphatic organs (thymus, spleen, tonsils, lymph

nodes)– diffuse lymphatic tissue -collections of

lymphocytes and other immune cells dispersed in the lining of the digestive and respiratory tracts and in the skin.

Immune Cells• Blood has 3 basic types of cells in it (as well as MANY

proteins & other chemicals)– Red Blood Cells : Carry oxygen – Platelets: Help form clots to stop bleeding – White blood cells: the “immune” cells that help identify &

fight infection • originate from precursor cells in the bone marrow and patrol tissues

by circulating in either the blood or lymphatics, migrating into connective tissue or collecting in immune organs.

• Immune system has cells that recognize proteins on the surface of other cells

– Look for certain proteins that identify cells as self – Look for certain proteins that are definitely “not self”

Immune Cells• Lymphocytes (2 major types)

– one of the most important cells of an immune response– B cells- arise & differentiate in the bone marrow & give rise to

plasma cells that secrete antibodies into the extracellular fluid, which bind to antigens

– T Cells-differentiate in the thymus; 3 subtypes:• T helper cells (CD4+)-act through secretion of soluble short-range

effector molecules, called cytokines that will stimulate B cells and macrophages

• T cytotoxic cells (CD8+)-attach directly to target cells tokill them• Natural Killer Cells- play an important role in innate immunity; important

in elimination of tumors and virus-infected cells

Immune Cells • Phagocytes –

– provide innate cellular immunity in tissues and initiate host-defense responses

– Three types:• 1) Neutrophils : important in the phagocytosis of pathogens &

generate extracellular fibers called NETS that kill bacteria without the need for phagocytosis

• 2.) Macrophages--derived from monocytes that enter the tissue from the blood, phagocytose bacteria and tissue debris; release systemic cytokines that ↑ body temp

• 3.) Dendritic Cells- derived from bone marrow. They are phagocytic when they are immature. When mature they have the capacity to bind antigens on their surface and are able to present these antigens & activate resting “T-cells” & initiating adaptive immune responses.

Immune Cells • Other cells

– 1) Mast Cells—connective tissue cell. It is found near blood vessels. They cells release histamine, and other substances that cause inflammation & anaphylaxis

– 2)Eosinophils- weak phagocytes, important against parasitic worms, discharges destructive contents of cytoplasmic granules

– 3) Epithelial cells- cells that line structures. Important in blocking entry of foreign cells & therefore crucial in defense

Organs/tissues of the Immune System• Specialized organs and collections of tissue where

lymphocytes interact with non-lymphoid cells– Important to maturation and/ initiation of adaptive immune responses.– Two types

• 1. Primary Immune Organs--where stem cells develop and differentiate into mature B-cells and T-cells:

– a) Bone Marrow—B-cells mature in the bone marrow– b) Thymus—a large organ in the cranial chest in which T-cells mature

• 2. Secondary Immune Organs—these organs trap cells or pathogens arriving from sites of infection and antigen is presented to lymphocytes to stimulate adaptive immune responses

– a) Lymph Node—situated along the extensive drainage system of lymph vessels, they serve to filter the lymph fluid before returning it to the bloodstream

– b) Spleen—serves as a filter for the blood, it is involved in clearance and mounting of immune responses against blood-borne antigens

Innate vs. Adaptive Immunity

• Innate: • Born with it• Does not change over a lifetime• Same response each time

• Adaptive: • Develops over time, not born with it (starts around 6

months of age) • “Learns” • Has “memory”

Natural “Innate” Immune System – All multi-cellular organisms have some type of

innate immune system– Includes physical, mechanical and chemical

barriers (skin, mucus, saliva, acids, hairs/cilia) – Also includes some white blood cell responses– Does not change over a lifetime, same response

each time – Not dependant on prior exposure– Fast – Is often turned on by the Adaptive Immune

System

Natural “Innate” Immune System – Immune cells/proteins:

– recognize common structures shared by many pathogens (germs)

– Do the same thing every time they are activated• Leads to inflammation • Some cells have roles in both Innate & Adaptive Immunity

– Cells that kill or “eat” invaders : Macrophages– Cells that release toxins: Mast Cells – Natural Killer T Cells– Cells that block entry: Epithelial Cells– Neutrophils, Eosinophils, Basophils

• Molecules present in body fluids• All help to destroy non self cells by breaking them apart or

busting them open– Lysozyme– Proteases– Complement

Adaptive “Acquired” Immune System

– Only present in vertebrates (animals with a backbone)

– Develops over time, “learns” and has “memory” – Slow– Key is that after initial exposure/response,

subsequent exposures lead to more vigorous and rapid responses s

-This is the principle behind immunization

Adaptive “Acquired” Immune System• Two types of Adaptive Immunity:

• 1. Cellular Response or Cell Mediated Immunity (CMI)• T-cells & macrophages are involved

• Helper T Cells – recognize bad cells• Killer T cells- help destroy bad cells• T cells regulate the activities of B cells, T cells, and other cells

participating in immune responses.• provide help for antibody production by B cells• the effectors of antigen-specific cell-mediated immunity• CMI is important in the elimination of cells infected with pathogens

that replicate intracellularly (eg, viruses, mycobacteria, and some bacteria) and cells exhibiting aberrant differentiation (eg, neoplasms)

• CMI also destroys allogeneic (non-self) cells (graft rejection)

Adaptive “Acquired” Immune System• 2. Humoral Response

• Antibodies are involved • B lymphocytes “B cells”

• Make antibodies , which are protein “markers” that attach on to bad cells & mark them for destruction

• Primary humoral immune response happens when an antigen is encountered by the host for the first time.

– Virgin B cells need to be activated and proliferate before an effective immune response can be generated

– This primary response may be too slow to protect against many pathogens. The innate immune system may be utilized to limit microbial replication at the onset of infection.

• Secondary humoral immune response results from the activation of a memory B cell

– is faster and more effective in halting the progress of infection

Question

• 830: The nurse is assisting in administering immunizations at a health care clinic. The nurse understands that an immunization will provide– A. protection from all diseases– B. Innate immunity from disease– C. Natural Immunity from disease– D. Acquired immunity from disease

Answer

• D: Acquired immunity – Immunizations stimulate B cells to make

antibodies against a disease. This will prompt a rapid response the next time the host encounters that disease, ideally preventing infection

– Innate & natural immunity are essentially the same thing. If you had natural immunity to a disease you wouldn’t need immunizations! But natural immunity is non-specific

Immune Deficiency• Any loss of function of any part in the immune

system will make an individual more susceptible to infections

• Certain infections are typical for certain types of immune system problems

• Immune deficiencies can be: – present from birth– develop as results of infections or diseases that

damage the immune system – caused by drugs that suppress the immune system

Congenital Immune Deficiencies• Over 70 different types, but rare• Genetic, born without certain components of

the immune system• Some are severe, i.e. “Bubble Babies”

• Typically result from problems with both T-cells & B-cells “Severe combined immunodeficiency” or SCID

• Some are mild and can go undetected • Defects in certain types of antibodies, called IgA, can

cause slightly more colds & respiratory infections

Diseases Causing Immune Deficiency

• Some diseases weaken the immune system and make a patient more susceptible to infection– Diabetes: high blood sugars not only damage skin & blood

vessels (making it easier for bad stuff to enter), but the high “sugar” is like food for infections

– Cancers: some cancers are caused by abnormal growth of immune cells. Although there are a lot of the cells, they don’t work right (leukemia)

– Autoimmune diseases (discussed later) – Malnutrition: lack of proper vitamins & nutrients can

damage specific parts of the immune system

Infections Causing Immune Diseases• Any severe infection can “weaken” the immune

system & make people more susceptible to other infections

• Chickenpox• Measles• Tuberculosis • Mononucleosis• Hepatitis

• Some infections infect the immune cells directly – HIV (discussed more later)

Drugs Causing Immune Deficiencies• Cancer treatments “chemotherapy”• Anti-rejection drugs

– After getting transplants, people must take these drugs forever

– Body’s immune system recognizes the transplant as “foreign” and will destroy it if not suppressed

– However, they are at increased risk for getting infections because the immune system is suppressed

– Common anti-rejection drugs: – Cyclosporine -Tacrolimus (Prograf)– Prednisone -Mycophenolate mofetil (CellCept)– Azathioprine (Imuran) -Sirolimus– Cyclophosphamide (Cytoxan) -Methorexate (MTX)

Drugs Causing Immune Deficiencies• Prednisone and other corticosteroids

– Used frequently to suppress the immune system when it’s causing more harm than good

• Bad allergic reactions • Asthma exacerbations • Autoimmune disorders

• Drugs to treat autoimmune diseases “Immunologics” – Since the diseases are caused by immune cells attacking “self”

instead of “enemy” , the only treatment is to suppress the immune system

• Very active area of new drug development • Have developed very specific treatments • Basically use the immune system’s mechanics to destroy itself• Most drugs end in “-imab”

Question

• 828: The nurse is assisting in planning care for a client with a diagnosis of an immune deficiency. Which of the following should be incorporated as a top priority in the plan of care? – A. Protecting the client from infection– B. Providing emotional support to decrease fear– C. Encouraging discussion about lifestyle changes– D. Identify factors the decreased the immune

function

Answer

• A. Protect the client from infection– All are good things to consider in the plan of care,

but immunocompromised patients are at increased risk for infection

– Protection would include proper immunizations, hand washing, immunizations for family members or close contacts, avoiding sick people, avoiding raw/undercooked foods

Hypersensitivity & Allergies

• Allergy: an abnormal response to certain substances that do not normally cause such a response– An allergic “response” is caused a hypersensitivity

reaction– There are 4 basic types of hypersensitivity

reactions

Type I Hypersensitivity

• What we think of as an “allergic” reaction – Spectrum from seasonal allergies to hives, to full blown

anaphylaxis – Involves a type of antibody known as “IgE”

• IgE developed primarily to help us fight parasites • IgE is “too sensitive” in people with Type I Hypersensitivity • IgE can recognize common substances, like pollens, animal dander,

dust mite feces & trigger a response

– IgE activation triggers mast cells to “degranulate” (release their contents)-> mostly histamines & leukotrienes

• These molecules cause inflammation

Type I Hypersensitivity• Anaphylaxis

– a serious allergic reaction that is rapid in onset and may cause death

• Skin symptoms (90%): flushing, itching, urticaria (hives), and angioedema• Respiratory symptoms (70%): nasal discharge, nasal congestion, change in voice

quality, sensation of throat closure or choking, cough, wheeze, and dyspnea• Gastrointestinal symptoms (40%): nausea, vomiting, diarrhea, and crampy

abdominal pain• Cardiovascular symptoms(35%) : dizziness, tachycardia, hypotension, and

collapse

– Treatment: Think “ABC’s” • Epinephrine 1mg/ml: inject 0.5ml IM in thigh (may repeat) • Airway support with oxygen • 2 large bore iv’s & fluids • Antihistamines

Question

• 827: The client is brought to the ER and is experiencing anaphylaxis from eating shellfish. The nurse implements which immediate action?– A. Maintain a patent airway– B. Administer a corticosteroid– C. Administer epinephrine – D. Instructing the client on the importance of

obtaining a Medic-Alert bracelet

Answer

• A. Maintaining a patent airway • Always think of ABCs before anything else • Next would be epinephrine, then likely get iv’s

& give fluids, antihistamines & steroids

Question

• 829: A client calls & states he was just stung by a bumblebee. The client is afraid of a severe reaction because his neighbor had just such a reaction a week ago. The most appropriate action is– A. Advise the client to soak the site in hydrogen peroxide – B. Ask the client if he ever sustained a bee sting before – C. Tell the client to arrange for ambulance transport to the

nearest ER – D. Tell the client not to worry about the sting unless

difficulty breathing develops

Answer • The book says B • (ask if he ever sustained • a bee sting in the past)

– True bee sting allergies are IgE mediated anaphylactic responses. In order to have a significant amount of IgE present that responds to bee stings, you need to have been exposed to it previously

– However, this really isn’t the best answer. Almost half of severe anaphylactic bee stings are in people with no recollection of past stings

– A better answer would be to ask the patient if they have any signs of anaphylaxis (see list)

Type II Hypersensitivity

• Causes destruction of red blood cells (RBCs) • Two classic types

– 1. ABO incompatibility• Give someone blood that “doesn’t match”

– 2. Drug induced hemolytic anemia• Some drugs can cause antibodies in the body to suddenly

recognize proteins on their own RBCs as “non self”

• End result: the body uses something called “complement” to destroy the RBCs (burst them open)

Type III Hypersensitivity• Immune Complex Deposition • Slow process, develops over days to weeks

– Starts as a normal response, an antibody attaching to an antigen – Normally these complexes are cleared by phagocytes – When they aren’t promptly cleared, these complexes can activate all

sorts of other inflammatory markers – These complexes tend to collect in the joint spaces

• Serum sickness: rash, fever, malaise, and joint pain/swelling

• Arthus reaction: joint pain & fevers • Lupus

Type IV Hypersensitivity• Cell mediated or Delayed type Hypersensitivity• Involve T cells, not antibodies

– T-cells aren’t immediately sensitive, they have to be “sensitized” or previously exposed

• first exposure takes at least 48-72 hours to react, faster in subsequent exposures

• Skin typically tends to be very involved

– Tuberculosis testing uses type IV sensitivity – Contact dermatitis – Transplant rejection – Steven’s Johnson disease

Hypersensitivity

• Highlight: Latex Allergy– Very important in healthcare settings as many medical

supplies contain latex – 5-10% of healthcare workers have latex allergies. People

exposed to latex more often have a higher rate of allergy – Allergy to proteins in the milky sap of the rubber tree used

to make natural latex. People can often have other food allergies

– Can cause a contact dermatitis (Type IV) reaction or can lead to anaphylaxis (Type I reaction)

– Need to assess latex allergies in all patients

Question

• 834: Which client type is most at risk for developing latex allergy? – A. Hairdressers– B. The homeless– C. Children in day care centers– D. Individuals living in group homes

Answer

• A. Hairdressers– The question is getting at the fact that those

exposed more often to latex have the highest risk for developing latex allergies. You’d probably have to go to a lot of salons to know that hairdressers wear latex gloves frequently why preparing hair dyes. This seems rather unfair, a more fair answer would be food workers.

Question

• 836: You are ordering home health supplies for a patient with a latex allergy. Which should be a relatively safe order for this patient? – A. Elastic bandages– B. Adhesive bansdages– C. Brown Ace bandages– D. Cotton pads & silk tape

Answer

• D. Basically, anything stretchy may have latex/rubber in it. Adhesive bandages should be relatively safe as well, although some of the older ones can have rubber. A better thing would be to ask for “latex free” products. Most healthcare products are well labeled about containing or being free of latex these days due to visibility for this issue (& lawsuits…)

Autoimmune Diseases

• Results when there is a failure of the body to recognize its own cells as “self”

• T & B cells go through extensive selection to try & ensure they don’t respond to self

• However, through a combination of genetic predisposition & environmental conditions, sometimes autoimmunity results

• Many diseases have at least a component of autoimmunity

Question

• 834: In determining risk factors associated with latex allergies, which food allergy is commonly associated with latex allergy?– A. Eggs– B. Milk– C. Yogurt– D. Bananas

Answer

• D. Bananas– This isn’t a self evident question,

although the other 3 answers are pretty similar, making banana the likely choice

– Other associated food allergies are: tropical fruits, grapes, avocado, potatoes, hazelnuts, chestnuts

AutoimmunityOrgan

• Thyroid

• Pancreas• Adrenal Gland• Hair• Skin• Muscle

Disease• Hashimotos• Graves’ disease• Type I diabetes • Addison’s disease• Alopecia• Vitiligo• Multiple Sclerosis

Rheumatoid Disease• Rheumatology

• specialists in diseases affecting the joints, muscles bones & connective tissue

• Many of theses diseases are autoimmune diseases• Often are associated with certain markers

– Systemic Lupus Erythematosis (SLE) : Type III hypersensitivity where antigen/antibody complexes form in connective tissues around the body (marker- ANA)

– Rheumatoid Arthritis: body attacks synovial lining of joints (marker- rheumatoid factor, CCP)

– Rheumatic Fever: develop antibodies against heart muscles after strep infection

– Systemic Sclerosis (Scleroderma)– Vasculitis– Sjogren’s Syndrome– Ankylosis Spodylitis

Question

• 825: A client is suspected of laving systemic lupus erythematous (SLE). The nurse monitors the client, knowing that which of the following is one of the initial characteristic signs of SLE? – A: weight gain– B. Subnormal temperature– C. Elevated red blood cell counts– D. Rash on the face across the bridge of the nose

& on the cheeks

Answer:D. Butterfly RashNot much else causes a butterfly (Malar) rash,

however only about 30% have it at presentation

Question

• 831: The nurse is assigned to care for a client with systemic lupus erythematosus (SLE). The nurse plans care knowing this disorder is– A. A local rash that occurs as a result of an allergy– B. A disease caused by overexposure to sunlight– C. In inflammatory disease of collagen contained

in connective tissue – D. A disease caused by the continuous release of

histamine in the body

Answer

• C: an inflammatory disease of collagen contained in connective tissue – Part of a group of diseases called “connective

tissue diseases” – Autoimmune disease that effects nearly every

organ in the body

Question

• 832: The nurse is caring for a patient with SLE. The nurse reviews the doctor’s orders expecting to note that which of the following medications is prescribed– A. Antibiotic– B. Antidiarrheal– C. Corticosteroid– D. Opioid analgesic

Answer

• C. Corticosteroid– This isn’t technically always correct. The question

is trying to hint at the fact the steroids are potent inhibitors of the immune system, and when the immune system is over-reacting (as in autoimmune disease) we place people on steroids to try & suppress the immune system.

– Long term, however, we use other medications (“steroid sparing agents”) to try & get people off of steroids as they have lots of long term side effects

HIV/AIDS• Human Immunodeficiency Virus -> the virus that

causes Acquired Immunodeficiency Syndrome (AIDS)

HIV/AIDS• The virus infects CD4 positive (helper) T Cells • We monitor HIV patients by following their CD4

counts. CD4 <200 =AIDS• The virus is spread through body fluids and does not

live long outside of the body• Eventually, the destruction of T cells makes the host

susceptible to many infections

Opportunistic Infections• Infections seen commonly in

AIDS patients or any patients with severely compromised immune systems– Protozoa: Pneumocystis jiroveci

(AKA PCP)– Fungal infections especially

Candida– Cancers: Kaposi’s sarcoma arises

from HSV (virus)– Viral infections: CMV

Kaposi’s Sarcoma

HIV/ AIDS Meds

• Target different areas

HIV/AIDS Therapy

• Must combine multiple medications – HAART: “Highly effective Active Antiretroviral

Therapy” – Nothing is curative – Eventually virus develops resistance

Question

• 841: A client has AIDS and was diagnosed with cutaneous Kaposi’s sarcoma. How is this diagnosis confirmed?– A. swelling in the genital area– B. Swelling in the lower extremities– C. Punch biopsy of the lesion– D. Appearance of reddish-blue lesions on the skin

Answer

• C. Punch biopsy– This is always the way to “confirm” a skin

diagnosis – There are few things that cause reddish-blue

cutaneous lesions in AIDS patients however and this is almost certainly Kaposi’s even without the biopsy

Lyme Disease

• It’s unclear why the text placed Lyme Disease in this section, it’s not an immunologic disease

• It’s an infection caused by a type of bacteria called a spirochete.

• This bacteria, Borrelia burgdorferi, lives on the deer tick and is injected into humans when an infected tick feeds on a host

Lyme Disease• In some people, B. burgdorferi manages to

escape detection/eradication by the immune system

• This causes the disease “Lyme Disease”-> 3 stages – 1st: Days to months: “bulls-eye”

rash & flu-like symptoms – 2nd: Weeks later: joint pain, heart

disease, nerve damage– 3rd: Joint swelling/destruction

– Treatment: doxycycline

Question

• 837: Which of the following would you include in instructions on Lyme Disease? – A. Lyme disease is caused by a tick carried by deer– B. Lyme Disease is caused by contamination from

cat feces– C. Lyme disease can be contagious by skin contact

with an infected individual– D. Lyme disease can be caused by the inhalation of

spores from bird droppings

Answer

• NONE– The book says “A” but this is technically incorrect– The disease is caused by a BACTERIA, B.

burgdorferi which is transmitted by a tick that lives on deer & mice

Question• 839: A woman arrives & states she was just

bitten by a tick & would like to be tested for Lyme disease. In addition to ensuring proper removal of the tick, what would you tell the patient?

• A. Refer her for a blood test immediately• B. Tell here there are no tests available to test for Lyme

disease• C. Tell her it is not necessary to test unless arthralgias (joint

pain) develops• D. Tell her to return in 4-6 weeks because testing before

this time is not reliable

Answer• None are technically correct

– There is a blood test to look for evidence of antibody to Lyme disease, however, it takes 4-6 weeks for these antibodies to develop (Choice D)

– Many people in Lyme endemic areas have some antibodies to Lyme Disease and a positive test does not necessarily mean active disease

– Lyme disease should not be diagnosed solely on the basis of blood testing. Lyme disease serologic testing is inadvisable in the absence of epidemiologic evidence of exposure to B. burgdorferi AND clinical findings that are compatible with a diagnosis of Lyme disease (ie target lesions)