Which type of lymphocytes directly attack infected cells?

Cytotoxic T cells play a crucial role in the immune response by directly attacking and destroying infected cells, particularly those infected by viruses or other intracellular pathogens. These cells recognize infected cells through specific receptors that bind to antigens presented by major histocompatibility complex (MHC) molecules on the surface of the infected cells. Once recognition occurs, cytotoxic T cells release cytotoxic granules that contain enzymes, leading to the destruction of the infected cell.

This functionality is essential for controlling infections and eliminating cells that have been altered by pathogens. In contrast, memory B cells are primarily involved in the secondary immune response by remembering pathogens for faster antibody production upon re-exposure. Helper T cells assist in orchestrating the immune response by stimulating other immune cells but do not directly kill infected cells. Regulatory T cells help maintain immune system balance and prevent autoimmune responses without engaging in the direct attack of infected cells. Thus, cytotoxic T cells are uniquely specialized for the direct assault on infected cells, making them vital for effective immune defense.