What is the main purpose of the T cells in the immune system?

The main purpose of T cells in the immune system is to eliminate infected cells. T cells play a crucial role in the adaptive immune response, particularly in identifying and destroying cells that have been infected by viruses or other intracellular pathogens. The effector subsets of T cells, including cytotoxic T lymphocytes (CTLs), recognize infected cells through specific antigens presented on the surface of these cells via Major Histocompatibility Complex (MHC) molecules. Once activated, cytotoxic T cells can directly induce apoptosis (programmed cell death) in these infected cells, thereby halting the spread of the infection.

While other elements of the immune system, such as B cells, are responsible for antibody production, T cells have a more direct role in cellular immunity. Enhancing phagocytosis is more related to the activity of other immune cells, like macrophages and neutrophils, and memory of pathogens is generally related to both B and T cells; however, the primary function of T cells is their targeted action against infected host cells. This specificity is vital for controlling and eliminating infections, making their primary purpose centered on cell-mediated immunity.