Effect of CCA on accessory cell activity was examined in immune response with recombination systems consisting of plastic adherent and G-10 passed murine splenocytes. CCA (1-10 μg/ml) showd no significant effect on those systems. In addition, treatment with CCA (1-10 μg/ml) and addition of plastic adherent cells resulted in no significant increase in Con A induced-plastformation of murine splenocytes. These findings suggests that macrophage is not involved in modulation of immune response by CCA.