Answer :
Activated T cells undergo clonal expansion forming active helper T cells, which activate B cells and cytotoxic T cells, and memory T cells, remaining dormant until re-exposure. Other options are incorrect as they describe processes or outcomes inconsistent with the roles of helper or memory T cells. So the correct option is a) Clonal expansion; Helper T cells activate B cells and cytotoxic T cells, while memory T cells remain dormant until re-exposure.
Once T cells become activated, their fate is determined by the type of cytokines they are exposed to from antigen-presenting cells (APCs). Specifically, activated T cells undergo clonal expansion to form active helper T cells and memory T cells. Helper T cells, including TH1 and TH2 cells, perform various functions in the immediate immune response by activating B cells and cytotoxic T cells, and by managing immune responses through cytokine release.
Memory T cells, in contrast, are programmed for long-term survival. They 'remember' a specific antigen so that they can mount a rapid and strong response upon re-exposure to the same antigen. Thus, the correct option for the question is a) Clonal expansion; Helper T cells activate B cells and cytotoxic T cells, while memory T cells remain dormant until re-exposure.
- b) Maturation does not accurately describe the process of T cells transforming into helper and memory cells, and helper T cells do not secrete antibodies—this is the function of B cells turned plasma cells; memory T cells do not phagocytose pathogens.
- c) Apoptosis describes programmed cell death, which is not the process through which active helper and memory T cells are made; helper T cells are pivotal to the immune response, not programmed for cell death.
- d) Differentiation into cytotoxic T cells or dendritic cells is not the fate of activated helper T cells; they differentiate into specific helper T cell types or memory T cells, not into entirely different cell types.
Therefore, the correct option in the final answer is a) Clonal expansion; Helper T cells activate B cells and cytotoxic T cells, while memory T cells remain dormant until re-exposure.
