Immune Disorders

Question 1

Define hypersensitivity

Answer 1

inappropriate or exaggerated immune response

Question 2

Define Type I (immediate) hypersensitivity

Answer 2

-quick reaction, 2-30 mins
-T-dependent B cell activation starts the sensitization process
-plasma cells produce IgE against the allergen
-IgE attaches to mast cells, basophils, and eosinophils
-subsequent exposure to the allergen results in the degranulation of mast cells, basophils, and eosinophils and inflammatory response
-can be systemic or localized

Question 3

How are Type I hypersensitivities diagnosed?

Answer 3

Skin prick test

Question 4

Define Type II hypersensitivity

Answer 4

-antibodies and complement lyse target cells
-happens in 5-12 hours
-antigens are located on the surface of a cell or tissue (incompatibility of blood cells)
-results in cell lysis
-activation of complement system via IgG or IgM

Question 5

Define Type III immune (complex-mediated) hypersensitivity

Answer 5

-nonphagocytized complexes of antibodies and antigens trigger complement activation leading to inflammation, and causes neutrophils to release damaging enzymes.
-3-8 hour onset
-antigens that activate it are soluble
-complement and a particular ration of antibody to antigen are key
-result of viral, protozoa, and bacterial infections
-chemotaxis attracts neutrophils which degranulate and cause damage in blood cells

Question 6

Examples of Type 1 hypersensitivities

Answer 6

food/seasonal allergies/environmental allergens

Question 7

Examples of Type 2 hypersensitivities

Answer 7

transfusions and Rh incompatibilities, drug-induced cytotoxicity

Question 8

Examples of Type 3 hypersensitivities

Answer 8

-pneumonitis, glomerulonephritis, and arthritis
-systemic lupus erythematosus and rheumotoid arthritis

Question 9

Define type IV (delayed) hypersensitivity

Answer 9

-onset in 1-2 days
-previous sensitization results in T cell and macrophage migration towards antigen
-delayed hypersensitivity cells and memory T cells are involved.

Question 10

Examples of Type IV hypersensitivity

Answer 10

PPD test for TB and allergic contact dermatitis (poison oak), graft rejection, and multiple sclerosis

Question 11

Distinguish between systemic and localized reactions.

Answer 11

localized in one area
systemic is body-wide

Question 12

Which types of cells degranulate with Type I hypersensitivities? Which chemical mediator (cytokine) plays a large role?

Answer 12

Mast cells, basophils and eosinophils
histamine

Question 13

Describe blood incompatibilities. Which type of hypersensitivity does this correspond to?

Answer 13

Incompatibility between antigens on RBC and antibodies produced or Rh factor.
Type II

Question 14

Describe the factors that lead to hemolytic diseases of the newborn (aka erythroblastosis fetalis).

Answer 14

Rh- mother sensitived to Rh+ blood during first pregnancy. In second pregnancy if baby is Rh+, IgG will cross placenta and attack blood of newborn.

Question 15

Describe the role that memory T cells play in Type IV hypersensitivity.

Answer 15

Retain memory of antigen and become sensitized.

Question 16

Distinguish between allografts, autografts, and xenografts.

Answer 16

Allograft- transplanting organs or tissue within same species
Autograft- tissue transplant from one part of body to another on same person
xenograft- transplanting tissue/organs between different species

Question 17

Define privileged sites and give examples.

Answer 17

Less likely to reject tissue because of lack of blood supply/lymphatic vessels or contain a high amount of immunosuppressant molecules

Brain, cornea, testes, uterus, and thymus

Question 18

Describe MHC typing

Answer 18

donor-receipiant match. Looking for a compatible match between MHC auto-antigens, especially those on white blood cells.

Question 19

corticosteroids/glucocorticoids

Answer 19

inhibits the inflammatory response by inhibiting prostaglandin and leukotrine release and also suppresses T cell production.

ex. prednisone, cortisone, dexamethasone

Question 20

cytotoxic drugs

Answer 20

prevent mitosis and cytokinesis. Prevent the manufacture of precursors for DNA replication or nucleic acids

ex. methotrexate and azathioprine

Question 21

cyclosporine

Answer 21

Inhibit T cell function and prevents the production of interleukins. Given in combo with prednisone to prevent graft rejection

Question 22

lymphocyte-depleting therapies

Answer 22

Antibodies destroy activated T cells (anti-lymphocyte globulin) or monoclonal antibodies that are specific for the receptor for IL-2 found on T cells.

Question 23

Define autoimmune disease and give examples.

Answer 23

Body fails to distinguish between self and non self and attacks own cells

grave’s disease, diabetes type 1, rheumatoid arthritis, Chron’s disease

Question 24

Distinguish between primary and secondary immunodeficiency diseases.

Answer 24

Primary- genetic and present at birth (SCID)
Secondary- acquired due to environment or immunosuppressant drugs, or microbes

Question 25

Describe some opportunistic infections that are associated with AIDS.

Answer 25

pneumonia, Salmonella infection, candidiasis, toxoplasmosis, and tuberculosis (TB)

Question 26

Describe the characteristics of HIV and its mechanisms of pathogenicity.

Answer 26

-enveloped SSRNA in the retroviridae family and lentivirus genus
-RNA converted to DNA through reverse transcriptase and incorporated into host cell