Which type of cell is capable of directly attacking and killing other cells?

Cytotoxic T-cells play a critical role in the immune response by directly attacking and destroying infected or cancerous cells. They are equipped with receptors that can recognize specific antigens presented by these abnormal cells, allowing them to initiate a targeted attack. Once activated, cytotoxic T-cells release perforins and granzymes, which create pores in the membrane of the target cells and induce programmed cell death, or apoptosis.

Helper T-cells primarily serve to activate and regulate other immune cells rather than directly kill them. B cells are responsible for producing antibodies that neutralize pathogens but do not directly kill cells. Memory cells, which can be derived from either B or T cells, are crucial for long-term immunity, allowing the immune system to respond more rapidly to previously encountered pathogens, but they do not have direct cytotoxic functions.