Chapter 4 Immunopathology
2 List key facts about T lymphocytes



3 List key features of B lymphocytes


4 List key features of natural killer (NK) cells


7 List key features of cytokines


10 What is the pathogenesis of hypersensitivity reactions?

11 What are the characteristics of type I hypersensitivity (anaphylactic) reactions?

12 Are the type I hypersensitivity reactions localized or systemic?
Type I hypersensitivity reaction may cause a localized or a systemic reaction.

13 What is the pathogenesis of localized type I hypersensitivity reactions?
These reactions involve the interaction of three cell types:

First exposure leads to a sensitization and priming of the T and B cells, which interact and produce IgE that binds to the surface of mast cells in tissues. Upon second exposure to the same antigen, cross-linking of IgE on the mast cells occurs. Cell surface changes stimulate two sets of reactions (Fig. 4-1).

14 What occurs during the immediate degranulation of mast cells?


15 Which mediators are released from mast cells in a delayed manner?
These mediators, known as secondary mediators and released 6 to 12 hours later, include:

16 What are the symptoms associated with type I hypersensitivity reactions?
The symptoms depend on the route of exposure, dose of antigen, and the target organ sensitivity (Fig. 4-2).





17 What are the characteristics of type II hypersensitivity (cytolytic) reactions?
Antigen is present on the surface of the target cell. It may be intrinsic antigen (e.g., Rh D blood antigen) or antigen adsorbed on the cell surface from the environment (e.g., drugs acting as haptens). The antibody interaction with the antigen elicits three reactions (Fig. 4-3):



18 List important diseases caused by type II hypersensitivity cytotoxic reactions




19 What are the characteristics of immune complex–mediated hypersensitivity (type III) reactions?



20 List the most important diseases caused by type III hypersensitivity reaction






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