Cellular Immunity

T lymphocytes origin in bone marrow and then migrate to the thymus where they mature and differentiate.

There are several types of T lymphocytes, Helping T cells amplify immune response, supressor T cells – restrain it, cytotoxic T cells– destroy affected cells. T lymphocytes recognize only those antigens that are presented on other cell’s surface and bound with major histocompatibility antigens. This way they can find for example cells attacked by a virus. Such cells have viral antigens on their surface. Recognizing the antigen initiates process of destruction of modified cell. Helper T cells influence immune reaction by secreting hormone-like substances called interleukins (IL). There are at least 13 of them. New interleukins are still being discovered. IL-1 stimulates T cells and cause fever. Presence of IL-2 activates cytotoxic T cells also called natural killers (NK). NK cells destroy foreign cells by a lytic mechanism (bursting them).