| Abstract: | Attempts were made to break the tolerance of murine transplantation antigens of strain A in CBA mice by adoptive transfer of: 1) normal, syngeneic (CBA) lymphoid cells, or 2) moderate doses of sensitized, syngeneic (CBA anti-A) lymphoid cells followed later by high doses of CBA anti-A cells. Both kinds of attempt failed. Tolerance could be broken when a large enough dose of sensitized cells was given. Prior “immunization” of CBA mice tolerant to A with small doses of CBA spleen cells protected against doses of sensitized cells otherwise successful in breaking tolerance. Determinations of anti-recognition structure (anti-RS) antibody and of alloantibody activities in sera of tolerant mice, of mice which were successful in defending tolerance, and of mice in which tolerance could be abolished revealed an important role for anti-RS antibodies. No clear role could be assigned to alloantibodies present in the same sera. The function of anti-RS antibodies was shown by the failure of spleen cells from immunized tolerant mice to recognize tolerated antigen. This suggests that anti-receptor antibodies are active in neutralizing receptors of responding lymphoid cells emerging from a stem cell reservoir. |
