What is a delayed hypersensitivity reaction characterized by? - ProProfs Discuss
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What is a delayed hypersensitivity reaction characterized by?



A. Edema without a cellular infiltrate
B. An infiltrate composed of neutrophiis
C. An infiltrate composed of helper T cells and macrophages
D. An infiltrate composed of eosinophils

This question is part of Block 9 Hypersensitivity MCQs
Asked by Chachelly, Last updated: May 31, 2020

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Chachelly

Chachelly

Answered Mar 05, 2018

An infiltrate composed of helper T cells and macrophages

DTH is type 4, which involves Tcells, macrophages IFN-g and TNF-a Type IV hypersensitivity is often called Delayed Type Hypersensitivity as the reaction takes two to three days to develop. Unlike the other types, it is not antibody mediated but rather is a type of cell-mediated response. CD4+ helper T cells recognize antigen in a complex with either type 1 or 2 major histocompatibility complex. The antigen-presenting cells in this case are macrophages that secrete IL-12, which stimulates the proliferation of further CD4+ T cells. CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Type 1 cytokines, thus mediating the immune response. Activated CD8+ T cells destroy target cells on contact, whereas activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells.
 

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