[Sensitivity of the process of the formation of antigen-induced B-suppressors to DNA synthesis inhibitors].

The injection of 5 X 10(7) sheep red blood cells (SRBC) to CBA and (CBA X C57BL/6)F1 mice was accompanied by the formation of antigen-induced B-suppressors (AIBs) in the spleen of the animals on day 7. When transferred to syngeneic intact recipients, AIBs inhibited their response to SRBC (control). Methotrexate in a dose of 2.5 mg/kg, cytozar in a dose of 1000 mg/kg and 5-fluorouracyl in a dose of 100 mg/kg, injected to donors simultaneously with SRBC (group A), had no influence on the number of IgM-forming cells and, when introduced on day 5 after the injection of SRBC, decreased the number of such cells in donors (group B) as determined by testing the donors' response on day 7. The suppressor activity of AIBs obtained from the donors of group A was equal to that of the control, while AIBs obtained from the donors of group B had lower suppressor activity in comparison with the control. These results suggest that the proliferation of the precursors of AIBs occurs between days 2 and 5 of immune response and the formation of AIBs themselves, between days 5 and 7.