unit 14- disorders in immunity

Explain the basis for the ABO blood groups, and what type of antibody to the ABO antigens different individuals might have

-"A" type blood cells have A antigens and B antibodies -"B" type blood cells have B antigens and A antibodies -"O" type blood cells have neither A nor B antigens and both A and B antibodies -"AB" type blood cells have A and B antigens and no antibodies

Identify which blood types are considered universal donors and universal recipients.

-AB is considered the "Universal Recipient" -O is considered the "Universal Donor"

Provide highlights about the Arthus reaction and serum sickness.

-Arthus reaction: localized reaction at the site of injection due to inflamed blood vessels in the vicinity of any injected antigen -Serum sickness: systemic reaction throughout the blood and settle into various tissues causing destruction at the site (due to neutrophils degranulating) -Similar, but different from anaphylaxis because o Depend on IgG, IgM, IgA rather than IgE o Require large doses of antigen o Symptoms are delayed rather than immediate

Explain what severe combined immunodeficiency is and discuss currently available therapeutic approaches

-Complete absence of lymphocyte stem cells in the bone marrow. gene therapy—insertion of normal genes to replace the defective genes

Discuss the mechanism of action of "allergy shots".

-Desensitization - controlled injections of allergen (small but increasing doses every two weeks) o Produces IgG antibodies which block the allergen from binding IgE on mast cells -Drugs which block allergies - o Corticosteroids (inhibit lymphocytes) o Antihistamines - block histamine o Aspirin - blocks prostaglandin o Cromolyn - prevents degranulation of mast cells o Epinephrine - opens airways in an asthma attack o Leukotriene inhibitors - ie., Advair

List the major immune system components involved in Type II hypersensitivity.

-IgG and IgM antibodies tag cells (or target cells) for destruction -Complement Activation - causes lysis of targeted cells

Briefly describe two methods for diagnosing allergies.

-In vivo (in the living organism) - Skin test - small amounts of allergen are injected or scratched into the skin and monitored for wheal response (bumps) -In vitro (in the living tissue outside the body) o Serological tests - for IgE levels (RAST, radioallergosorbent test) o Leukocyte histamine release test o Differential blood cell count o Elevated blood levels of tryptase (released by mast cells during allergic response)

Name three conditions that can cause secondary immunodeficiencies.

-Infection -radiation -Chemotherapy

ingestant

-Ingestant: allergens which enter the gastrointestinal tract (food, drug)

inhalent

-Inhalant: allergens which enter the respiratory tract (dust, dander, pollen)

Distinguish between primary and secondary immunodeficiencies.

-Primary Immunodeficiencies: present at birth (congenital) and usually stemming from genetic errors -Secondary immunodeficiencies: acquired after birth caused by natural or artificial agents

Specify how Type III hypersensitivity is similar to, and also differs from, Type II hypersensitivity.

-Type II targets cells using antibodies attached to the targeted cell - targets the cells for destruction -Type III targets cells using antigen-antibody (Ag/Ab) complexes which are of intermediate size and which cause neutrophils to migrate to the area that they get caught in and degranulate - causing damage to tissues.

Provide the names for four different sources of graft material.

-autograph: self -isograft: identical twin -allograft: close match from same species -xenograft: different species

identify the four types of overreaction to antigens

-type I: immediate reactions - hay fever (IgE) -type II: antibody-mediated - blood type incompatibilies (IgG & IgM) -type III: immune complex reactions - serum sickness (IgG & IgM) -type IV: cell mediated cytotoxic - contact dermatitis

allergen

Allergen - an antigen which allergic individuals are sensitive to

contactant

Contactant: allergens which enter via the skin (chemicals, dyes, latex)

A positive tuberculin skin test is an example of antibody-mediated inflammation.

False: example of type IV hypersensitivity, delayed reaction. No memory Bcells

Describe the pathogenesis of contact dermatitis.

First exposure o Allergen enters the skin and is engulfed by macrophages just under the skin o Macrophages engulf, process, and present antigen to T-helper cells which proliferate and differentiate into many T-helper1 cells (Sensitized) Second exposure o Allergen is processed and presented by macrophages to T-helper cells o T-helper cells proliferate and differentiate into T-helper1 cells and memory cells o T-helper 1 cells activate macrophages o Macrophages secrete cytokines which cause the contact dermatitis (delayed hypersensitivity reaction on the skin)

name two major categories of immune dysfunction

Hypersensitivity (overactivity): - takes the form of allergy and autoimmunity Hyposensitivity or immunodeficiency (underactivity): - immune system is incompletely developed, suppressed, or destroyed

Explain under what circumstance the Rh factor can be problematic for newborn babies.

If the mother is Rh- and the fetus is Rh+ and the mother has already been sensitized to the Rh+ antigen by a previous pregnancy

Describe the sequence of events after secondary exposures to allergens.

Primary exposure - also called the "Sensitizing Dose" -Allergen is phagocytized, processed, and presented to a T-helper cell. -T-cell is activated and presents allergen (or secretes cytokines) to activate a B-cell. -B-cell proliferates and differentiates in to Plasma cells (which produce IgE antibodies rather than IgM or IgG antibodies) and Memory cells -IgE antibodies attach via the Fc portion of the Ab to the cell membrane of a mast cell. Secondary exposure - also called the "Shocking Dose" -Allergen is encountered for the second time and binds to Memory cells - which "re-sensitize" the body (see Sensitizing Dose) to the allergen -Allergen also binds to the free Fab (antigen binding) region of IgE Ab on sensitized Mast cells. -When several adjacent Ab are bound with allergen, the cell degranulates. -Degranulation releases chemical mediators which cause allergic symptoms (hives, itchy, red, watery eyes, nasal congestion, puffiness around eyes, sneezing, headache, and sometimes difficulty breathing).

explain why systematic anaphylaxis is so serious

Systemic anaphylaxis involves a severe, systemic reaction which affects the respiratory and circulatory systems. Persons with a severe anaphylactic reaction can go into anaphylactic shock and stop breathing. Death can occur within 15 minutes if not treated.

Antibody-mediated degranulation of mast cells is involved in anaphylaxis.

T

Contact dermatitis can be caused by proteins found in foods.

T

Rejection of transplanted tissue is dependent on MHC/HLA markers.

T

T cells are associated with type IV hypersensitivities.

T

Graves' disease

The underlying cause of Graves' disease is the attachment of autoantibodies to receptors on the thyroxin-secreting follicle cells of the thyroid gland. The abnormal stimulation of these cells causes the overproduction of this hormone and the symptoms of hyperthyroidism, which affect nearly every body system.

An example of a type III immune complex disease is a.serum sickness. b.contact dermatitis. c.graft rejection. d.atopy.

a

systemic lupus erythematosus (SLE), or lupus.

autoantibody-autoantigen complexes appear to be deposited in the basement membranes of various organs. Kidney failure, blood abnormalities, lung inflammation, myocarditis, and skin lesions are the predominant symptoms.

Theoretically, type _____ blood can be donated to all persons because it lacks _____. a.AB, antibodies b.O, antigens c.AB, antigens d.O, antibodies

b

The contact with allergen that results in symptoms is called the a.sensitizing dose. b.degranulation dose. c.provocative dose. d.desensitizing dose.

c

The direct, immediate cause of allergic symptoms is the action of a.the allergen directly on smooth muscle. b.the allergen on B lymphocytes. c.allergic mediators released from mast cells and basophils. d.IgE on smooth muscle.

c

B cells are responsible for which of the following? a.asthma b.anaphylaxis c.tuberculin reactions d.both a and b

d

Pollen is which type of allergen? a.contactant b.ingestant c.injectant d.inhalant

d

Production of autoantibodies may be due to a.emergence of forbidden clones of B cells. b.production of antibodies against sequestered tissues. c.infection-induced change in receptors. d.possibly all of these.

d

Rheumatoid arthritis is an ____ that affects the ____. a.immunodeficiency disease, muscles b.autoimmune disease, nerves c.allergy, cartilage d.autoimmune disease, joints

d

Type II hypersensitivities are due to a.IgE reacting with mast cells. b.activation of cytotoxic T cells. c.IgG-allergen complexes that clog epithelial tissues. d.complement-induced lysis of cells in the presence of antibodies.

d

Which disease would be most similar to AIDS in its pathology? a.X-linked agammaglobulinemia b.SCID c.ADA deficiency d.DiGeorge syndrome

d

Myasthenia gravis

is a syndrome caused by autoantibodies binding to the receptors for acetylcholine, a chemical required to transmit a nerve impulse across the synaptic junction to a muscle. The immune attack so severely damages the muscle cell membrane that transmission is blocked and paralysis ensues.

clonal selection theory

the immune system of a fetus develops tolerance by eradicating all self-reacting lymphocyte clones, called forbidden clones, while retaining only those clones that react to foreign antigens.