Question

True or False: T4 helper cells activate the cellular imunne response which includes cytotoxic lymphs, granulocytes, and macrophages.

Answer 1

T helper cells are T cells that play an important role in adaptive immune response. Activation of T helper cells occurs when antigen presenting cells (APC) bind foreign peptides on pathogen. This signal 1 is due to MHC protein that is present on surface of APC. B7 molecules are expressed by APC. These co-stimulatory molecules will bind to CD28 on T helper cells. APC that activate T helper cells express class II MHC molecules. The Class II MHC molecules will bind to T cell receptor on T helper cells. The T helper cells then stimulate B cells to produce antibodies against the foreign peptide and then destroy the bacteria. It can also produce cytokines that stimulate cytotoxic T cells to attack infected cells.

There are two subset of T cells- TH1 and TH2 involved in these responses. THI helper cells when activated, will secrete cytokines such as TNF alpha and IFN gamma. These cytokines will stimulate phagocytes (macrophages) to kill the pathogen by ingesting them and forming phagolysosomes. TNF alpha and IFN gamma are also involved in activation of T cytotoxic cells.

Interleukins such as IL-4, IL-13, etc produced by TH2 cells will activate B cells. B cells can produce antibody molecules. These antibodies stimulate mast cells, basophils and eosinophils (granulocytes).

Right Choice: True.