Human monocyte cytotoxin is not identical with lymphoblastoid lymphotoxin.

Mononuclear phagocytes and lymphocytes can both synthesize cytotoxins which kill certain tumor cell lines and recent evidence suggests that these cytotoxins may be identical. In this study, human monocyte cytotoxin and lymphoblastoid lymphotoxin have been critically compared in terms of specificity, physicochemical characteristics and antigenicity. Despite their similar pattern of reactivity with a panel of cell lines, lymphotoxin was less readily adsorbed than monocyte cytotoxin by tumor cells. The cytotoxins could also be distinguished by their behavior on high performance liquid chromatography and by the failure of antibody to monocyte cytotoxin to react with lymphotoxin.