What is the primary role of cytotoxic T-lymphocytes (CTLs) in immune response?

The primary role of cytotoxic T-lymphocytes (CTLs) in the immune response is to directly kill infected host cells that display foreign antigens on their surface. This process is essential for controlling and eliminating intracellular infections, particularly those caused by viruses or certain intracellular bacteria.

CTLs are equipped with T-cell receptors (TCRs) that recognize and bind to specific antigens presented by major histocompatibility complex (MHC) class I molecules on the surface of infected cells. Once a CTL recognizes its target, it releases cytotoxic granules containing perforin and granzymes. Perforin creates pores in the target cell membrane, allowing granzymes to enter and induce apoptosis, or programmed cell death, effectively eliminating the infected cell. This targeted approach prevents the spread of the pathogen and is a critical aspect of the adaptive immune response.

In contrast, other options focus on different immune functions. For instance, neutralizing pathogens typically involves antibodies produced by B cells, while supporting the function of other immune cells can refer to the role of helper T cells. Each component of the immune system plays a distinct role in overall immune protection, but the specific function of CTLs is centered on the direct elimination of infected cells.