Inhibition of leukocyte migration in agarose by KC1 extracts of a human melanoma cell line grown in serum‐free medium

KCl extracts of Melanoma 14, a human melanoma cell line grown in chemically defined serum-free medium, inhibited leukocyte migration in 19/36 (53%) patients with malignant melanoma. Only 4/23 (17%) controls with non-melanoma malignancies and 4/25 (14%) normal subjects with no history of cancer were similarly inhibited. Only 2/27 melanoma patients tested against KCl extracts of normal muscle tissue excised from the donor of Melanoma 14 were significantly inhibited. Patients with Stage I (localized) melanoma and patients with Stage III (generalized) melanoma reacted with roughly equal frequency but the number of patients in each group was too small for meaningful statistical analysis. Leukocytes from the donor of Melanoma 14 were tested in a completely autologous system against extracts of Melanoma 14 tissue culture cells and extracts of autologous muscle and were specifically inhibited by the Melanoma 14 tissue culture extract (Migration Index = 0.67) but not by the extract of normal muscle (Migration Index = 0.96). Only 7/32 (22%) melanoma patients were significantly inhibited by an extract of non-melanoma tumor. These results suggest that melanoma-associated antigens are present in soluble extracts of this tumor line. Such extracts could provide a continuing source of standard melanoma-associated antigens for purification and chemical characterization and for diagnostic and prognostic tests in patients with malignant melanoma.