Release of tumor-associated antigens by murine melanoma cells.

Synthesis and release of radiolabeled macromolecules and tumor-associated antigens (MAA) by murine B16 melanoma was studied by pulse labeling cells in culture with 3H-leucine. Approximately 36% of newly synthesized macromolecules and 44% of newly synthesized MAA were released in 48 hr. MAA release was slightly, but consistently, more rapid than the average release of other macromolecules. Release of MAA did not result solely from cell death since it was greater than that of 51Cr-labeled molecules and cell viability was over 98%. The rate of release of newly synthesized MAA was not significantly influenced by cell replication. However, synthesis of MAA was much greater during the logarithmic than the stationary phase of cell growth, suggesting a concomitant increase in the amount of MAA available for release. These findings indicate that antigens and other macromolecules can be rapidly released by viable tumor cells.