URGENT: Two immune system questions: Activated T-helper cells aid in humoral imm
ID: 71182 • Letter: U
Question
URGENT: Two immune system questions:
Activated T-helper cells aid in humoral immune responses by releasing cytokines which promote antibody production, phagocytosis, neutralization and apoptosis. Which parts of this statement are false and why? I know cytokines activate B cells and cytotoxic T cells, and the interferons are cytokines as well.
Membrane receptors associated with cd4, cd8, cytotoxic t cells and helper t cells do not recognize antigenic determinants of pathogens in the ECF space. Why is this true? Are these cells not present in the ECF?
Explanation / Answer
The cytokines released by activated T helper cells are involved in the promotion of antibody production, phagocytosis and neutralization. But T helper cells can’t induce apoptosis. T cytotoxic cells are involved in inducing the apoptosis in a cell which got infected with virus by adhering to the virally infected cell with the help of specific peptides displayed on MHC I molecules, to prevent it to generate more viruses and further spreading in the body.
The main defense mechanism used to encounter antigen in extracellular fluid (ECF) is humoral immunity, where antibodies secreted by B cells recognizes and bind to antigens. Whereas T cells cannot detect antigenic determinant in ECF as T cells can recognize fragments of antigenic determinants which are processed and presented along with MHC self antigens on infected cells. These cells will not be found in the ECF.
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