A suppressor mechanism controlling lymphocyte recruitment.

The duration of the inductive effect of an antigen (alum-precipitated trinitrophenyl-keyhole limpet haemocyanin) was measured, in the presence and absence of responding spleen cells, by transfering a test population of spleen cells to irradiated mice at various times relative to antigen injection. Using allotype-congenic mice, the response of a test (Iga) population was estimated in the presence of responding (Igb) cells. In the absence of responding cells the inductive effect fell to 10% of the peak value in 9-10 days, but in their presence it reached this level in less than 5 days. Removal of T cells from the responding (Igb) population reduced their suppressive efficacy. It was concluded that B lymphocyte recruitment is curtailed not by the elimination of antigen but by an active suppressor mechanism involving suppressor T cells.