Distinction of allogeneic immunity from tumor-specific immunity in man

Tissue-cultured melanoma cells and their autogenous fibroblasts were used for microcytotoxicity testing for the prevalence and activity in normals and in melanoma patients of: (1) "killer" lymphocytes; (2) blocking effects of transplantation and progressor melanoma sera; and (3) anti-tumor IgG antibody. Three of nine (33 per cent) of the melanoma patients possessed specific lymphocytotoxicity against melanoma cells, and 12 of 34 (35 per cent) normal individuals possessed allogeneic lymphocytotoxicity against both melanoma and fibroblast cells. Sera from melanoma patients could block melanoma-specific systems but, unlike transplant sera, did not block allogeneic kill. Sera from all normals and eight of nine melanoma patients were unreactive to melanoma and fibroblast cells by mixed agglutination. Sera from one melanoma patient reacted to both cell lines. These findings suggest a reappraisal of the role of allogeneic immunity in testing for tumor immunity.