When an antigen or mitogen is presented by antigen presenting cell (APC), specific T-cells can recognize and respond to these antigens or mitogens. They will start dividing (proliferation) and can also release specific cytokines and chemokines. The proliferation can be detected by adding ³H thymidine to the dividing cells. This ³H is incorporated into the DNA only during replication of a cell (1). The uptake is thus proportional to the number of cell divisions.

Proliferation of Human Mononuclear Cells with 3H-Thymidine