Effect of stimulation and blockade of mononuclear phagocyte system on the induction of suppressor T cells of delayed footpad reaction to SRBC in mice

The role of mononuclear phagocyte system (MPS) in the induction of suppressor T cells which depress the delayed footpad reaction to sheep erythrocytes (SRBC) was studied in mice in which MPS was blocked or stimulated. Colloidal carbon and diethylstilbestrol were used for blockade and stimulation respectively. Adoptive transfer of suppressor T cells was achieved by spleen cells of mice immunized intraperitoneally with varying doses of SRBC. In nontreated mice, 1 x 10 ⁹ SRBC were required to induce suppressor T cells, while 6 x 10 ⁸ could not induce the suppressor T cells. In MPS-blocked mice, however, even 6 x 10 ⁸ SRBC could induce the suppressor T cells. On the other hand, 3 x 10 ¹⁰ SRBC were required for the induction of suppressor T cells in MPS-stimulated mice. These results suggest that the activity of macrophages as scavenger cells modulates the subsequent induction of suppressor T cells after immunization with high doses of SRBC.