A demonstration of a strain related restriction effect in the formation of experimental metastases.

In view of the role of histocompatibility proteins in mediating many types of cell interaction it was decided to investigate their role in the formation of experimental metastatic deposits using the B16 mouse melanoma cell line. The expression of both major histocompatibility complex (MHC) Class I and Class II proteins was studied in vitro. Expression of both MHC Class I and Class II proteins was greater in the highly metastatic F10 cell line as compared with the poorly metastatic F1 line. Intravenous injection of cells into syngeneic and semi-allogeneic animals revealed a strain related restriction effect on tumour growth following intravenous injection. However, this was mediated by a locus other than H-2. No restriction of lung trapping of radiolabelled cells or local growth following intraperitoneal injection was found. It is suggested that non-H-2 Class I proteins may mediate some of the stages of metastatic tumour growth independent of the immune system.