Chapter 13: Immune System Disorders

Define immunodeficiency

lack of a properly functioning immune system

What is a primary (congenital) immunodeficiency?

error that affects one or more immune system factors and leads to deficient immunity from birth

What is a secondary (acquired) immunodeficiency?

starts out with a normal immune system and then experiences a decline in immune system rigor

Besides aging, what is the leading cause of secondary immunodeficiencies?

medical interventions

List four viruses that can potentially cause secondary immunodeficiencies

human immunodeficiency virus(HIV)

human T cell lymphotropic viruses

Epstein–Barr virus

measles

What is Kaposi sarcoma? Late-stage infection with which virus makes patients more susceptible to this disease?

it is a rare cancer, HIV makes patients more susceptible

What is the difference between prophylactic vs therapeutic immunotherapies?

prophylactic - try to prevent cancer

therapeutic - treat existing cancer

Define autoimmune disorder

immune system attacks healthy self tissues that should be left alone

What failure of the immune system leads to autoimmune disorders?

B and/or T cells lack of self-tolerance

Although not solidly confirmed, certain autoimmune disorders maybe linked to suspected infectious agents. Name the infectious agent that may be associated

Type 1 diabetes -

• Coxsackievirus B (cause of infectious myocarditis or inflammation of the heart muscle) is one possibly linked agent

Guillain-Barre syndrome

• Campylobacter jejuni (leading cause of bacterial diarrhea) may be involved

Rheumatic heart disease

• Streptococcus pyogenes (cause of streptococcal pharyngitis, “strep throat”) may have a role

Multiple sclerosis

• over 20 different viral agents have been proposed as linked to MS; examples include human herpesvirus 6 and Epstein–Barr virus

True or False. If the statement is “False”, correct it. Autoimmune diseases are usually straightforward in their diagnosis, often needing only one test to identify the disorder

False

What is the immunological cause of hypersensitivities?

inappropriate secondary immune responses

What is the hygiene hypothesis, and what are the likely results associated with it?

aims to explain why autoimmunity and allergy are more common in residents of developed nations than in residents of developing countries, proposes that in developed countries, ultra-clean water and food combined with common antibiotic usage and decreased infection incidence has decreased the biodiversity of people’s normal microbiota, thereby affecting how our immune system develops, increasing our risk for developing autoimmune disorders and allergies

What is the name of the classification system for organizing the four types of hypersensitivities?

Gell and Coombs classification system

Which type of hypersensitivity reaction is not mediated by immunoglobulins (antibodies)?

Type IV

Which type of hypersensitivity reaction is not associated with autoimmune disorders?

Type I

Define allergen and allergy

allergen

• any antigen that triggers IgE production and leads to allergy

allergy

• scenario in which the immune system fights off a perceived threat that would otherwise be harmless

Define sensitizing exposure

allergen exposure that triggers the immune system to produce IgE

During Type I hypersensitivity reactions, what cells degranulate during postsensitization exposures? What proinflammatory molecules are contained within the granules of these cells?

antibody-coated mast cells and basophils, contains histamine and leukotrienes

What is the difference between localized and systemic anaphylaxis?

localized - allergic reaction that tends to feature isolated symptoms such as watery eyes, a runny nose, or a confined rash

systemic - system wide immune response, can progress to anaphylactic shock

Define anaphylactic shock. How is it usually treated?

severe systemic anaphylaxis, sudden, severe, and life-threatening allergic reaction

treatment usually involves administration of epinephrine using an autoinjector (such as an EpiPen) followed by emergency medical care

When performing a blood test for exposure to an allergen, what is the test detecting? What do you think an increased IgE titer would indicate?

would indicate a possible or probable allergy

What is a wheal and flare lesion? What does it mean if an allergen yields a wheal and flare lesion when testing for an allergen during a skin prick test?

produced in skin tests if the patient has an allergy to the tested allergen, it means the person is allergic to the allergen

What is the goal of desensitization immunotherapy?

for the body to shift its immune responses to the allergen

What two antibody types mediate Type II hypersensitivity reactions? In general, what type of antigens do the antibodies bind to?

IgG or IgM binding to non-soluble antigens on the surface of a cell or within the extracellular environment

How do non-cytolytic reactions occur in Type II hypersensitivities? What are two possible outcomes that can occur?

autoimmune basis with antibodies interacting with a cell-surface receptor on self-cells, causes either a receptor inactivation or an overactivation

Which of the four classes of hypersensitivity reactions do blood group incompatibilities/transfusions reactions belong to?

Type II

What are the four most widely analyzed blood antigens? Where are the antigens found?

A, B, O, Rh, found on RBCs surface

What surface antigen(s) is/are on RBCs of a person with AB- blood?

A and B

When do hemolytic transfusion reactions occur? What is the outcome of these reactions?

immune response against incompatible transfused red blood cells, the body’s antibodies attacks the blood and kills those cells, can lead to death

Hank has type A+ blood but is transfused with type B+ blood. What will happen to Hank’s red blood cells? Why does this occur?

hanks RBCs will be attacked by the B antibodies in his body, the antibodies recognize the B antigens from the new blood as a foreign pathogen

What blood group is considered the universal recipient? Why?

AB+ because they can receive every type of blood

What blood group is considered the universal donor? Why?

O- because they are able to donate to everyone

What occurs during the first pregnancy of an Rh- mother and an Rh+ fetus? Does hemolytic disease of the newborn occur?

the Rh- mother is exposed to the Rh+ blood of the fetus during pregnancy or birth

is does not occur

What occurs during the second and subsequent pregnancies of an Rh- mother and an Rh+ fetus? Does hemolytic disease of the newborn occur?

maternal IgG antibodies cross the placenta and target fetal Rh+ red blood cells, leading to red blood cell lysis and severe anemia in the fetus

yes it does occur

What drug can be administered to an Rh- mother upon her first pregnancy with an Rh+ fetus to prevent sensitization to the Rh factor?

Rh(D) immunoglobin

What antibody types mediate Type III hypersensitivity reactions? In general, what antigens do the antibodies bind to?

IgG or IgM antibodies bind to soluble antigens to make an excessive number of antibody-antigen complexes

As Type III hypersensitivity reactions progress, what forms? Where are they deposited? What is the result of this?

relatively large antibody-antigen complexes form, deposited in tissues where they attract complement factors triggering massive inflammation

List five autoimmune diseases that are caused by Type III hypersensitivities

Systemic Lupus Erythematosus

Rheumatoid Arthritis

Scleroderma

Sjogren’s Syndrome

Poststreptococcal Glomerulonephritis

How does serum sickness develop?

the patient’s immune system recognizes the administered antivenom or antitoxin as foreign and antibodies form and attack it

What is the mediator of Type IV hypersensitivity reactions?

T cell mediated

Why are Type IV hypersensitivity reactions also called delayed hypersensitivity reactions?

because they slowly manifest over 12-72 hours after the stimulating antigen is encountered

List five autoimmune disorders that are caused by Type IV hypersensitivity reactions

Guillain–Barré syndrome

Hashimoto thyroiditis

type I diabetes

multiple sclerosis

celiac disease

What molecule triggers most nonautoimmune Type IV hypersensitivity reactions?

haptens - molecules that are on their own too small to trigger immune responses, but bind to host proteins, thereby becoming immunogenic and provoking an immune response

List four nonautoimmune Type IV hypersensitivity reactions

tuberculin skin test

contact dermatitis

transplant rejection

graft-versus-host disease

Define autograft, isograft, allograft, and xenograft. Which one is least likely to be rejected?

autograft

• transplants from self, like a self-skin graft from one part of the body to another location, lowest rejection reaction risk

isograft

• transplanted tissue that is genetically identical to the host, these grafts are accepted as “self” and typically safe from immune rejection

allograft

• tissue or organ transplants that are similar to the host, but not genetically identical

xenograft

• interspecies transplants (for example, implanting pig heart valves into a human heart)

What is an immune-privileged site? List four of these sites in the body

body sites in which transplants are the least likely to be rejected

eye, brain, uterus, and testicles

What is the difference between transplant rejection and graft-vs-host disease?

transplant rejection

• when the patient’s T cytotoxic cells detect that the tissue is foreign

graft-versus-host disease(GVHD)

• the graft attacks host tissues