Immunology Lecture 19 Hypersensitivity Diseases And Reactions

Front 1

What is Type 1 hypersensitivity

Back 1

Immediate hypersensitivity: IgE antibody mediated

Front 2

What is type 2 hypersensitivity

Back 2

Antibody-mediated: IgG anti-tissue antibody mediated

Front 3

What is type 3 hypersensitivity

Back 3

Immune complex-mediated: IgM/IgG antibody-mediated complexes

Front 4

What is type 4 hypersensitivity

Back 4

Delayed-type hypersensitivity: T cell mediated (CD4 and CD8)

Front 5

What type of hypersensitivity is seen in allergic reactions

Back 5

Type 1 IgE mediated; allergy and anaphylaxis

Front 6

What are the steps in the synthesis of IgE and sensitization step (primary antibody response)

Back 6

1. Dendritic cells are primary APC
2. Naive CD4 T cells develop into Th2 cells in association with MHC II
3. Th2 cells secrete IL-4 which promotes class switching to IgE. Memory B cells are produced
4. IgE binds to mast cells (FceRI receptor)

Front 7

What is the memory response in the allergic response

Back 7

1. Memory B cells have surface IgM that binds antigen
2. Th2 cells recognize these B cells, and secrete IL-4
3. B cells differentiate into plasma cells and secrete IgE, which binds to mast cells
4. Eosinophils and basophils also release preformed toxic molecules, as well as cytokines and inflammatory mediators

Front 8

What are the effects of IgE mediated allergic reactions

Back 8

1. Systemic anaphylaxis: vascular engorgement and asphyxia secondary to bronchial and larygeal constriction (1 hr duration)
2. Cutaneous anaphylaxis: Transient redness and swelling for 30 minutes

Front 9

What happens in the wheal and flare reaction

Back 9

There is an immediate reaction caused by IgE mediated mast cell degranulation. There is also a late phase reaction 6-8 after exposure, due to the leukotrienes and cytokines synthesized by IgE mediated activation of mast cells

Front 10

What are Rhinitis and asthma caused by

Back 10

Inhaled allergens

Front 11

What are urticaria, angioedema, and eczema reactions to

Back 11

Allergic reactions in the skin

Front 12

What is Atopy

Back 12

Exaggerated tendency to mount IgE responses to a wide variety of environmental allergens. Influenced by several genetic factors

Front 13

What are four major environmental factors that contribute to atopy

Back 13

1. Changes in exposure to infectious diseases in early childhood
2. Environmental pollution
3. Dietary changes
4. Allergen levels

Front 14

What are some examples of Type 2 hypersensitivity reactions

Back 14

Transfusion reactions, Hemolytic disease of the newborn, drug-induced hemolytic anemia

Front 15

What are some mechanisms by which antibodies against tissue antigens cause disease

Back 15

1. Opsonization and phagocytosis (hemolytic disease of the newborn, transfusion reactions)
2. C' and FcR-mediated inflammation and tissue injury (ab-mediated glomerulonephritis)
3. Abnormal responses without cell or tissue injury (Graves disease or Myasthenia gravis)

Front 16

What causes type 3 hypersensitivity reactions

Back 16

Deposition of immune complexes in blood vessels (systemic lupus erythematosis)

Front 17

What type of cell causes type 4 hypersensitivity

Back 17

T cell

Front 18

What are the mechanisms of T cell-mediated hypersensitivity reactions

Back 18

1. CD4 Th1 cells are sensitized. Upon subsequent exposure, they activate macrophages
2. CD8 CTL causes cytolysis