Journal of Leukocyte Biology 40:65-72(1986) Ganglioside Identification on Human Monocyte Membrane With Clostridium per fringens Delta-Toxin

Clostridium perfringens delta-toxin was first described as a hemolysin with a restricted lytic spectrum. A selective cytotoxicity of the delta-toxin was then found on rabbit leukocytes: peritoneal and alveolar macrophages were uni-formly killed, whereas thymocytes were essentially resistant. The toxin was shown to be specific for GM2 ganglioside or a GM2-like structure. In the present study we report the interaction of delta-toxin with human monocytes. A specific, saturable, and irreversible binding of 1251-delta-toxin was demonstrated. Bind-ing was inhibited by preincubation of the radiolabeled toxin with GM2 and with high amount of GM1 ganglioside. As judged by dye exclusion, no cytotoxicity was observed on freshly isolated monocytes, but when added at the beginning of a culture of human adherent cells, the cytotoxic effect was detected after 48 hours of culture. Taken together, these data indicate the presence of monosi-aloganglioside(s) at the surface of human monocytes, and suggest a possible reorganisation of such structure into the cell membrane when monocytes mature in vitro toward macrophage-like cells. Key words: macrophage, binding, huma