Immune disorders (2)-1

Immune disorders (2)-1 - 1 Hypersensitivity(Table18. A...

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Immune disorders-know key terms at start of chapter. 1. Hypersensitivity  (Table 18.1 and all animation quizzes for chapter 18) A. Type I-Anaphylactic hypersensitivity  (Fig. 18.1)  It is B cell mediated 1) Sensitization occurs when antigen (airborne or ingested) is first encountered. Antigen is processed and  presented by APCs. T helper cells are activated and B cells are fully activated to make IgE and  memory cells. 1. Antigen must be small 2. Proteinaceous   2) IgE is produced and circulates through the body. Antibodies bind to  mast cells in the tissues via  IgE  FcR on the surface of cells. 3) During the next exposure to the same antigen, antigen cross-links IgE on surface of mast cells, basophils  and eosinophils.  Crosslinking activates cells. 4) Release of granules causes response- histamine (increases permeability and dilation of blood capillaries,  increase of mucous production), leukotrienes (prolonged contractions of smooth muscle)  5) Additionally, the allergen activates memory cells are activated to produce more IgE and more memory  cells. 6) Response time is very rapid-Immediately to 30 minutes . 7) Types of Type I responses: a. Hives, also known as wheal and flare reaction. Fluid filled lesions where antigen has activated local mast cell degranulation. Local reaction, swelling. (Fig. 18.2) b. Hay fever-Mast cells in upper respiratory system degranulate to release molecules that enhance innate response: increased mucous, sneezing, swelling tissues. c. Asthma- constriction of smooth muscle in lower respiratory system due to release of histamine  from mast cells in  lungs. Leukotrienes and prostaglandins are responsible for increase mucous  production and bronchial spasms. d. Anaphylatic shock-systemic release of mediators causes peripheral blood vessels throughout body  to dilate, result in loss of blood pressure.   Treatment is epinephrine. 1
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8) Treatments: a. Induce a blocking antibody response  IgG (Fig. 18.3)  The IgG reacts with antigen before it can bind to IgE,  and therefore it blocks the IgE reaction b. Engineered anti-IgE antibodies  B. Type II- Antibody-dependent cytotoxic hypersensitivity  Type II and Type III are almost exactly alike 1) B cell (
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Immune disorders (2)-1 - 1 Hypersensitivity(Table18. A...

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