Humoral mediator of antigenic competition demonstrated in vivo.

To determine if a soluble mediator of antigenic competition could be demonstrated in vivo, various groups of mice received implants of intraperitoneal Millipore diffusion chambers containing normal spleen cells and sheep erythrocytes (SRC). Priming and boosting the chamber hosts so that a vigorous secondary immune response to horse erythrocytes (HoRC) coincided with chamber implantation resulted in the suppression of the anti-SRC response of the chamber-enclosed cells. Similarly, passive immunization of the chamber hosts with SRC-absorbed anti-HoRC hyperimmune serum suppressed the response of the chamber-enclosed cells to SRC. Thus, serum from hyperimmune mice contains a humoral suppressor substance which mediates antigenic competition.