__________ T cells are responsible for cell-mediated immunity.Multiple ChoiceHelperMemorySuppressorCytotoxic

Final Answer

Cytotoxic T cells are responsible for cell-mediated immunity.

Explanation

Cytotoxic T cells, also known as CD8+ T cells, play a vital role in the immune response by directly killing infected cells, cancer cells, and sometimes cells that are damaged in other ways. They recognize antigens presented on major histocompatibility complex (MHC) I molecules, which are present on all nucleated cells. When cytotoxic T cells bind to a target cell that presents a foreign antigen, they release perforin and granzymes, leading to the destruction of the target cell.

This process is crucial for eliminating intracellular pathogens, such as viruses, which hide inside host cells. The other options listed—memory T cells, suppressor T cells (or regulatory T cells), and helper T cells—have different functions. Memory T cells help ensure a faster response upon re-exposure to an antigen, suppressor T cells help regulate and maintain immune tolerance, while helper T cells (CD4+ T cells) assist other immune cells in responding effectively.