Membrane associated antigens of human malignant melanoma. II. Leucocyte migration studies with formalin fixed human melanoma cells.

The leucocyte migration test from caillary tubes was examined for its usefulness as an assay for cell-mediated immunity in melanoma patients. Formalin fixed melanoma cells either obtained from established cell lines or freshly excised tumors were used as antigen source. From a group of 33 melanoma patients 14 reacted positively (42%) when fixed cultured cells were used, whereas, no positive reactions were found in a group of 14 control donors. However, a considerable proportion of patients with chronic inflammatory processes of the skin reacted positively (4/17 = 24%). A smaller proportion of positive reactions were found in melanoma patients when fixed melanoma cells from excised tumors were used (1/16 = 6%). The positive results in the group with chronic inflammatory processes may be explained as reactions against melanoma associated, but not melanoma-specific, antigens. Three possible reasons are discussed for the low frequency of positive reactions with cells from excised tumors: 1. the cells used in this study display only a few of the antigenic determinants typical for malignant melanoma, 2. antigen expression is quantitatively lower. 3. the surface antigens are covered by blocking factors.