What type of T cell is generated in response to an exogenous antigen?

What type of T cell is generated in response to an exogenous antigen?

• A. T regulatory cells
• B. T cytotoxic cells
• C. T helper cells
• D. NK cells

Answer: (C)

The generation of T helper cells in response to an exogenous antigen is crucial for orchestrating the immune response. Exogenous antigens are those that originate outside the body, often from pathogens like bacteria or viruses. When these antigens are presented to naive T cells by antigen-presenting cells (APCs), such as dendritic cells, the interaction primarily occurs through the T cell receptor (TCR) recognizing the antigen displayed on major histocompatibility complex (MHC) class II molecules.

Once activated, T helper cells play a pivotal role in supporting other immune system components. They release cytokines that enhance the activity of B cells, promoting antibody production, and stimulate T cytotoxic cells, which directly kill infected or cancerous cells. This coordination is vital for effective adaptive immunity, particularly in responding to extracellular pathogens.

In contrast, T regulatory cells primarily function to maintain immune tolerance and prevent autoimmune responses rather than directly responding to exogenous antigens. T cytotoxic cells are primarily involved in recognizing and killing cells that present endogenous antigens, such as those from virus-infected or tumor cells, on MHC class I molecules. Natural killer (NK) cells are part of the innate immune system and do not rely on antigen presentation via T cell receptors