Human malignant melanoma cells: morphological and immunological variations

When cultured in vitro, human malignant melanoma cells proliferated in two patterns: In one the cells were polygoneal or spheroidal unequal in form and size, whereas in the other, the cells were elongated, fusiform, poorly delimited, with various degrees of atypism. Antisera to each of these two types of malignant melanoma cell cultures were raised in rabbits. The antiserum cytotoxic activity was assessed against 10 cultures of malignant melanoma cells, 10 mammary carcinoma, 2 fibrosarcoma and 10 normal skin fibroblasts. Prior and at intervals post surgery, the cytotoxic activity of serum from 10 patients with malignant melanoma was assessed against the above cell cultures. Based on their cytotoxic activities, the sera drawn from patients with melanoma thirty days after surgery had the highest cytotoxicity and could be classified into two groups similar to the rabbit antisera. Glycoprotein fractions were isolated from 3 M KCl extracts of the two melanoma cell types, i.e. from patients ShA and ZBJ. These glycoproteins stimulated 14C-2-thymidine uptake and DNA-polymerase activity of peripheral blood lymphocytes from post surgery melanoma patient. The glycoproteins had no effect on peripheral blood lymphocytes from normal donors.