Human melanoma growth in the peritoneal cavity of the athymic mouse--a model for in vivo study of cell-mediated immunity.

Intraperitoneal injections of 2 X 10(7) SH-Me cells (human metastatic melanoma cells)( to 20 Balb/c nu/nu mice (Group A) and 1 X 10(7) cells to 20 mice (Group B) were performed. All animals were studied clinicopathologically. Five animals in Group A were sacrificed serially, revealing marked tumor growth of the melanoma within the peritoneal cavity. These tumors grew in multiple nodular configurations and tumor ascites was present by the third week. The remaining 15 animals in Group A were allowed to progress and seven subsequently died with mouse viral hepatitis (MVH). These animals had suppressed tumor growth. The remaining eight animals died of peritoneal carcinomatosis with survival time of 24.1 +/- 5.0 days. Eight of the animals in Group B died of mouse viral hepatitis while the remainder died of peritoneal tumor without distant metastasis. Survival time in these animals was 23.8 +/- 2.6 days. Both 2 X 10(7) and 1 X 10(7) tumor cells injected intraperitoneally will constantly produce tumor nodules in non-MHV-infected nude mice with similar survival. This experimental model has proven useful for in vivo study to assess the immunoreactivity of melanoma patient cells reactive against target tumor cells.