Production of melanoma-associated antigen(s) by a defined malignant melanoma cell strain grown in chemically defined medium.

A human malignant melanoma cell strain, UCLA-SO-M14 (M14), was adapted to grow in serum-free, chemically defined medium (CDM). The 3 M KCl extract prepared from the CDM-grown cells (M-14-CDM) was assayed against leukocytes from melanoma patients, patients with other cancers, and normal donors by leukocyte migration inhibition (LMI). The leukocytes from 15 to 27 (56%) melanoma patients tested were LMI positive. In contrast, 4 of 18 (22%) other cancer patients and 5 of 30 (17%) normal donors leukocytes were LMI positive. One of 14 melanoma patients' leukocytes were LMI positive for a control 3 M KCI extract from autologous muscle. Comparative studies were performed with the M14-CDM extract and a 3 M KCI extract from a freshly biopsied tumor specimen from the donor of the M14 cell strain. Seven of 12 (58%) melanoma patients' leukocytes were LMI positive to the M14-CDM extract, but only 2 of 12 (17%) were LMI positive to the autologous melanoma tissue extract. Furthermore, only 100 to 300 mug protein of M14-CDM extract were required to educe delayed cutaneous hypersensitivity response in 6 of 8 (75%) melanoma patients and 0 of 5 lung cancer patients, but 500 mug protein from biopsied autologous melanoma tissue extract were needed to produce delayed cutaneous hypersensitivity response in 24 of 42 (57%) melanoma patients and 7 of 28 (25%) nonmelanoma cancer patients. These data suggest: (a) the M14-CDM cells synthesized melanoma-associated antigen(s) (MAA) in CDM; (B) the 3 M KCI extraction procedure effectively removed the MAA from the M14-CDM cells; (c) the M14-CDM cells were a more potent source of MAA than the surgical autologous melanoma specimen; and (d) the M14-CDM cells provided a continuous source of standard MAA.