Poliovirus-induced suppression of lymphocyte stimulation: a macrophage-mediated effect.

Poliovirus was shown to suppress the in vitro response of human mononuclear blood cells stimulated with phytohaemagglutinin (PHA), pokeweed mitogen (PWM), tuberculin purified protein derivative (PPD) or allogeneic cells. The suppression required infectious virus and the presence of macrophages. Experiments with combined cultures of human lymphocytes stimulated with PHA, PWM, PPD or allogeneic cells, and different numbers of autologous macrophages indicated that both lymphocyte stimulation and the inhibitory effect of poliovirus increased with increasing ratio of macrophages to lymphocytes. The response of human lymphocytes to PHA also was enhanced when autologous macrophages were replaced with murine macrophages. Mouse hepatitis virus inhibited this enhancing effect whereas poliovirus failed to do so. The findings confirm our previous suggestion that poliovirus inhibits stimulation of lymphocytes by suppressing the enhancing effect of macrophages.