hypersensitivity and T and B-cells

Question 1

Hypersensitivity Reactions

Answer 1

immune responses to antigens that can cause tissue damaging reactions, and resultant tissue lesions hypersensitivity disease

Question 2

Type I Hypersensitivity
what is it

immunoglobulin associated with type I

how Ig works and what it leads to (2)

Answer 2

1. Rapid response that follows reaction to antigen
2. Mechanism involved is related to formation of IgE (prior sensitization necessary)
3. IgE binds to receptor on mast cells & basophils, activating them to release histamine as a primary mediator & later other potent inflammatory mediators (prostoglandins, leukotrines)
4. this leads to lots of histamine> vasodilation>extreme drop in Blood Pressure
5. Can lead to anaphylaxis

Question 3

Hypersensitivity Type 1
Localized Reactions

what body parts they involve and what they cause

Answer 3

Involve upper respiratory tract and conjunctiva

- Cause itching, swelling, sneezing, and conjunctivitis

Question 4

Type I Hypersensitivity

General Reaction

Answer 4

associated with bronchial constriction & circulatory collapse, and anaphylaxis,

Question 5

Type II Hypersensitivity Reactions
which immunoglobulins are associated with type II

how they work

category of disease associated with type II and 3 specific disease examples

Answer 5

1. Involve IgG and IgMm in direct cytotoxicity
2. Involve antibodies binding directly to the surface of the cell, inducing the compliment system which leads to the target cell destruction via direct lysis or opsonization
3. Most autoimmune diseases: including hemolytic anemia, Graves disease, myesthenia gravis

Question 6

Type III Hypersensitivity
a.k.a.

what immunoglobulins are associated w/ type III and how they work

what kind of diseases are associated with type III- and 3 specific examples

Answer 6

1. a.k.a.- Immune complex diseases
2. Antigen-Antibody (IgG, IgA, IgM) complexes are formed in circulation and disposed in different tissues
   - presence of immune complexes in tissues activate the complement chemotaxis of neutrophils and release of neutrophil enzymes responsible for tissue damage
3. Autoimmune diseases such as systemic lupus erythmonatosis (SLE), experimentally induces vasculitis, and some types of glomerulonephritis

Question 7

Type 4 Hypersensitivity Reactions
description (and 1 disease)

how it works

Answer 7

1. cell-mediated immune response (no antibodies) w/sensitized lymphocytes as the ultimate cause of tissue injury (Sjogren syndrome)
2. Antigens are processed by macrophages and presented to cytotoxic T cells inducing their activation and release of mediators

Question 8

true or false; all hypersensitivity reactions involve antibodies

Answer 8

False. Type 4 reactions don’t involve antibodies.

Question 9

5 stages of B-cell maturation and what Ig associated with them

Answer 9

1. pre-b cells (no Ig)
2. early b-cells (M, D)
3. iso-type switching (AGE)
4. mature (GAM) - this complex is 95% imunoglobulins
5. plasma cells (generally activated by T-cells)

Question 10

how do B-cells get activated?

Answer 10

1. retain immunoglobulins attached to their surface membranes so when antigen comes along B-cell differentiates into plasma cells

Question 11

NK cells (3)

Answer 11

1. natural killer cells = null cells
2. 10-15% of all blood lymphocytes
3. first line of defense against neoplastic tumor and virus infected cells b/c they can lyse w/o prior sensitization

Question 12

complement systems associated with type II hyersensitivity reactions
direct lysis
opsonization

Answer 12

1. direct lysis- membrane attack complex - C5-9

2. enhancing phagocytosis -C3b