Which of the following is NOT a function of helper T-cells?

Helper T-cells, also known as CD4+ T-cells, play a crucial role in orchestrating the immune response by coordinating the activities of various immune cells. They perform several important functions, including stimulating B cells to produce antibodies, activating cytotoxic T-cells, and enhancing the activity of macrophages.

Helper T-cells do this primarily through the release of cytokines, which are signaling molecules that aid in communication between immune cells. These cytokines can stimulate B cells to differentiate and produce antibodies, which are essential for targeting pathogens. Additionally, helper T-cells help activate cytotoxic T-cells, enabling them to recognize and destroy infected or cancerous cells. They also enhance the phagocytic activity of macrophages, improving the immune response against invaders.

However, helper T-cells do not directly kill infected cells. This function is primarily carried out by cytotoxic T-cells, which can directly target and induce apoptosis (programmed cell death) in cells that are infected with viruses or have become cancerous. Therefore, stating that helper T-cells directly kill infected cells is incorrect, highlighting that this specific activity is outside their main role within the immune response.