The T cell-dependent period of the immune response to sheep erythrocytes.

To study the T cell-dependent period of the immune response of mouse spleen cells to sheep erythrocytes the co-operation between T and B cells was abrogated at different times during the in vivo or the in vitro response. The abrogation was performed by killing the T cells with anti-theta serum or anti-H-2 serum. The surviving cells were subsequently cultured in vitro and the number of IgM plaque-forming cells was determined each day. The results indicate that T cells play an important role during the first 3 days of the response in vivo. However, during the in vitro response the presence of the T cells is only required during the first 2 days. The difference between the response in vivo and in vitro is probably due to a synchronous start of the plasma cell development in vitro and a more asynchronous start of this process in vivo.