Inhibition of leukocyte migration by tumor-associated antigens in soluble extracts of human malignant melanoma.

Direct leukocyte migration inhibition (LMI) assays were performed to investigate whether cell-mediated immune reactions could be detected in response to tumor-associated antigens of human melanoma. The antigens were 3 M KCl-soluble extracts of different fresh melanomas, other cancers, and benign nevus tissue. A total of 48 of the 79 (61%) blood samples from melanoma patients (64 patients) reacted with extracts of melanoma tissue. Since the subjects were usually tested with two or three extracts, 57/134 (42%) tests with melanoma patients' leukocytes were inhibited by KCl extracts of melanoma tissue, whereas only 3/50 (6%) tests with leukocytes of normal donors and 4/27 (15%) with patients having other cancers gave positive results. No positive reactions were obtained when 13 melanoma patients were tested with a 3 M KCl extract of benign nevus tissue. Likewise, only 2/26 (8%) positive tests were obtained from melanoma patients tested with extracts of other cancers. Individuals in all stages of disease had similar incidences of positive reactions to the soluble melanoma extracts, except for patients with stage-1 disease who exhibited a somewhat higher incidence of reactivity. The highest incidence of reactivity was observed in patients before surgical resection of the tumor, and somewhat decreased reactivity was seen 0-14 days post surgery. The results indicate that the direct LMI assay may be used to measure cell immune reactivity against melanoma-associated antigens. Since many of the positive results were obtained with allogeneic extracts, the results also indicate that different melanomas possess common antigens.