Cell mediated immunity is carried out mainly by
- A. antibodies dissolved in the plasma
- B. B lymphocytes
- C. complement proteins
- D. T lymphocytes
Explanation
T cells act on cells rather than on free antigen, destroying virus infected cells, cancer cells and transplanted tissue by direct contact, which is why this branch is called cell mediated. Humoral immunity is the other branch, in which B cells give rise to plasma cells whose antibodies circulate in body fluids. The two branches cooperate, since helper T cells are needed to activate most B cells.