What type of T cells are often referred to as killer cells due to their ability to eliminate invading organisms?

Cytotoxic T cells are termed "killer cells" because of their primary role in directly attacking and destroying infected or malignant cells. They identify cells that have been compromised by pathogens, such as viruses, or that have become cancerous. Upon recognition, cytotoxic T cells release chemicals that create pores in the target cell's membrane or induce apoptosis, which is a form of programmed cell death. This targeted attack helps to maintain the integrity of the organism by eliminating cells that could otherwise propagate diseases.

Helper T cells, while crucial to the immune response, primarily assist other immune cells rather than directly destroying cells. Regulatory T cells play a role in maintaining immune tolerance and preventing autoimmune responses, rather than attacking cells. Memory T cells are responsible for long-term immunity, remembering past infections but not directly engaging in the destruction of pathogens. Overall, cytotoxic T cells are fundamental in the immediate response to infections due to their killer capabilities.