How do CD4 and CD8 T cells differ in function?

CD4 and CD8 T cells play crucial and distinct roles in the immune system, which is reflected in the correct choice. CD4 T cells, often referred to as helper T cells, primarily function to enhance the immune response. They do this by secreting various cytokines, which help activate and coordinate the activity of other immune cells, including B cells (which produce antibodies) and CD8 T cells, as well as macrophages and other parts of the immune system.

On the other hand, CD8 T cells, known as cytotoxic T cells, are tailored to directly target and kill infected cells, especially those infected by viruses or other intracellular pathogens. They do this by recognizing specific antigens presented by major histocompatibility complex (MHC) molecules on the surface of infected cells, and upon activation, they release cytotoxic granules that induce apoptosis in those infected cells.

This distinction is vital for an effective immune response. The helper functions of CD4 cells ensure that the immune system mounts a strong and coordinated attack, while the direct killing action of CD8 cells eliminates the infected cells harboring pathogens, thereby controlling and resolving infections.