Effect of antibodies against immunoglobulins and the theta antigen on the specific and non-specific stimulation of mouse spleen cells in vitro

Normal mouse spleen cells were stimulated in culture by phytohaemagglutinin (PHA), pokeweed mitogen (PWM), allogeneic cells; keyhole limpet haemocyanin (KLH) sensitized cells by the specific antigen. The stimulation of the cells was measured by [³H]thymidine incorporation into the TCA precipitable fraction of the cultures. In this system, the effect of treating the cells with an antibody against the theta antigen and an antibody against immunoglobulin, with or without complement, was investigated. Treatment of the cells with antisera and complement or without complement gave similar results. The secondary in vitro stimulation with soluble antigen KLH could be markedly reduced with both anti-θ and anti-immunoglobulin serum. The response to allogeneic cells in the mixed lymphocyte reaction was only reduced by anti-θ serum and not by anti-immunoglobulin serum. No definite effect could be demonstrated by either antibody on the non-specific stimulation by PHA or PWM.