hypersensitivity & immune deficiency

Question 1

hypersensitivity

Answer 1

excessive/inappropriate activation of immune system leading to production of antibodies/T cell responses that cause tissue injury and disease

Question 2

hypersensitivity reactions

Answer 2

disorders caused by immune responses

Question 3

allergy

Answer 3

hypersensitivity to exogenous antigens such as medicines, pollen, bee stings

Question 4

types of hypersensitivity

Answer 4

allergy, autoimmunity, alloimmunity

Question 5

autoimmunity

Answer 5

disturbance in immunologic tolerance of self-antigens – immune system develops auto-antibodies that damage its own tissue

breakdown of tolerance either due to alteration of antigen or idiopathic (more common)

no known tx – treat symptoms & suppress immune system

Question 6

alloimmunity

Answer 6

immune reaction to tissues of another individual, i.e. blood transfusion, organ transplant

Question 7

type I hypersensitivity

Answer 7

IgE mediated, causes mast cell degranulation (histamine release) – anaphylactic

IgE binds to Fc receptors on mast cells (cytotropic antibody)

Question 8

type II hypersensitivity

Answer 8

tissue-specific reactions (cells lyse) – cytotoxic

tissue cells destroyed by IgG/IgM & complement – antibody attaches to cell & causes antibody-dependent cell-mediated toxicity by NKs

Question 9

type III hypersensitivity

Answer 9

immune complex mediated – antigen-antibody complexes form in body fluid & are deposited in vessel walls/extravascular tissues

Question 10

type IV hypersensitivity

Answer 10

cell mediated – T cells attacking (does not involve antibodies) – delayed hypersensitivity

Question 11

hypersensitivity process

Answer 11

sensitization (first exposure), immune response, second exposure causes symptoms

Question 12

anaphylaxis

Answer 12

symptoms: respiratory difficulty due to vasoconstriction of pulmonary vessels, hives, vomiting, diarrhea, swelling of bronchial tract, low BP, shock

Question 13

histamine release mechanisms

Answer 13

H1 receptors cause bronchial constriction & increase vascular permeability (tx diphenhydramine)

H2 receptors cause increased gastric secretion (tx pepsin)

Question 14

symptoms of type I hypersensitivity

Answer 14

itching, urticaria, conjunctivitis, rhinitis, hypotension, bronchospasm, dysrhythmias, GI cramps/malabsorption

Question 15

type I hypersensitivity management

Answer 15

tests: food challenge, skin/lab tests

Question 16

desensitization

Answer 16

IgG blocking antibodies – small quantities of allergen injected to build resistance to reaction

Question 17

tx type I hypersensitivity

Answer 17

antihistamines, desensitization, steroids, bronchodilators, anti-leukotrienes, anti-IgE antibody, epinephrine (acute reactions only)

Question 18

examples of type IV hypersensitivity

Answer 18

acute graft rejection, TB skin test, contact allergic reactions, collagen destruction in RA, destruction of thyroid in Hashimoto disease, contact dermatitis from poison ivy

Question 19

examples of type III hypersensitivity

Answer 19

SLE, RA, some acute glomerulosclerosis, Raynauds phenomenon

Question 20

examples of type II hypersensitivity

Answer 20

blood transfusion reactions, hemolytic disease of the newborn, Goodpasture disease

Question 21

sequestered antigen

Answer 21

self-antigens not normally seen by immune system, can cause autoimmune reaction

Question 22

systemic lupus erythematosus (SLE)

Answer 22

chronic multisystem inflammatory disease – autoantibodies created against nucleic acids, erythrocytes, coagulation proteins, phospholipids, lymphocytes, platelets, etc.

most common in African-Americans & females

Question 23

symptoms of SLE

Answer 23

arthralgias/arthritis, vasculitis, rash, renal disease, hematologic changes, cardiovascular disease

presence of antinuclear antibodies (ANA) – diagnostic

Question 24

transient neonatal alloiummunity

Answer 24

fetus expresses parental antigens not found in mother

Question 25

ABO blood antigens

Answer 25

antibodies formed at birth from IgM

Question 26

transplant rejection

Answer 26

caused by MHC/HLA – HLA typing done to prevent antibody formation (matches patient/donor antigens)

Question 27

types of rejection

Answer 27

hyperacute, acute, chronic

Question 28

hyperacute rejection

Answer 28

immediate, rare – preexisting antibody to antigens in graft/transplant

Question 29

acute rejection

Answer 29

cell-mediated response against unmatched HLA antigens, occurs w/in days-months – type IV

Question 30

chronic rejection

Answer 30

occurs after several months/years – slow organ failure – weak cell-mediated type IV reaction

inflammatory damage to endothelial cells of vessels

Question 31

AIDS

Answer 31

blood-borne pathogen, currently increasing faster in women than men – effective therapies have made it a chronic disease

disables CD4 receptors on helper T cells & reverses CD4/CD8 ratio

Question 32

clinical manifestations of HIV

Answer 32

serologically negative, serologically positive but asymptomatic, early stage, AIDS

helper T cells < 200 cells/cubic mm

Question 33

transmission of HIV

Answer 33

blood, breast milk, sperm

Question 34

highly active antiretroviral therapy (HAART)

Answer 34

reverses transcriptase inhibitors, protease inhibitors – tx HIV

Question 35

tx HIV

Answer 35

HAART, entrance inhibitors, integrase inhibitors, vaccine is in development

Question 36

graft-vs-host disease (GVHD)

Answer 36

T cells in graft are mature & capable of cell-mediated destruction of tissues w/in recipient – not a problem if patient is immunocompetent

Question 37

evaluation of immunity

Answer 37

CBC with differential, quantitative determination of immunoglobulins, assay for total complement, skin tests

Question 38

tx immunodeficiencies

Answer 38

gamma globulin therapy, transplantation/transfusion, soluble immune mediators, gene therapy