Release into culture medium of membrane-associated, tumor-specific antigen by B-16 melanoma cells.

Serum-free supernatant fluids from monolayer cultures of B-16 mouse melanoma cells were found to contain a soluble membrane associated tumor-specific antigen. The 100,000 g supernatant of the culture fluid induced an antibody response to the B-16 cells both in rabbits and in the mouse strain of origin (C57Bl/6J). Similar supernatant fluids derived from an unrelated cell line (L-929) or from normal C57Bl/6 fibroblasts did not contain the B-16 specific material. Preliminary results indicate that the B-16 specific material is a protein of low molecular weight which is released into the culture fluid chiefly by living cells and, to a lesser extent, by autolysing cells.