Antigen-dependent induction of a non-specific humoral factor blocking rosette-forming cells in experiments in vitro and in vivo

Isologous serum of CBA mice immunized with rabbit immunoglobulins (ARIS) contained a factor capable of inactivating rosette-forming splenocytes (RFC) in vitro from the same strain of mice immunized with SRBC. When mouse SRBC immunization was carried out against the background of ARIS injection the court of RFC to SRBC at the peak of immune response was 30% of that of mice injected with SRBC and normal isologous serum. A decrease of RFC count was the result of disappearance of the theta-negative RFC. Passive ARIS immunization failed to influence the antigen-induced proliferation of the antibody-forming cells and the synthesis of antibodies against SRBC.