Effect of IL-2 and indomethacin on the activation of suppressor cells induced by tetanus toxoid.

Experiments were performed to delineate the mechanism by which tetanus toxoid (TT) suppresses the immune response. A CD4+ cell has been shown to suppress the PHA response (18). TT suppresses the phytohemagglutinin (PHA) blastogenic response and pokeweed mitogen (PWM) induction of IgM and IgG in a dose-dependent fashion. The suppression is partially reversed by indomethacin or interleukin-2. The tumor necrosis factor had no effect. TT induced the suppression within 36 h and the immunosuppressive activity induced could downregulate the response of fresh syngeneic cultures of peripheral blood leucocytes. We conclude that TT can induce nonspecific suppressor cells that can dampen mitogen responses which has important implications in the development and usage of vaccines.