Macrophage dependence of galactose oxidase induced transformation of human lymphocytes

The role of macrophages in the transformation of human lymphocytes by the mitogen galactose oxidase was studied. Monocyte depleted, purified T or B cells did not undergo blastogenesis after treatment with galactose oxidase. When galactose oxidase-treated purified T cells were cultured with macrophages, a slight proliferative response was obtained. B cells treated similarly showed no response. When macrophages were treated with galactose oxidase, and then T & B, T, or B cells were added, proliferative responses were observed in all 3 categories. Finally, supernatants of media in which galactose oxidase-treated macrophages were cultured also demonstrated the property of stimulating lymphocyte transformation. These results are consistent with current concepts of mitogen "presentation" and the elaboration of soluble factors by macrophages in mediating the activation of lymphocytes in response to stimulating agents.