Cell-mediated responses are implemented by T lymphocytes. The major functions of T cells can be divided into two categories:
- The first (cytotoxicity) is to lyse cells expressing specific antigens
- The second (delayed hypersensitivity) is to release cytokines, thereby triggering an inflammatory response
These two types of cells are used to combat intracellular pathogens such as viruses, certain bacteria, and parasites inaccessible to antibodies.