Guinea pig cell-mediated tumor immunity: the chromium release assay detects both cytolysis and serum blocking for syngeneic chemically-induced tumors.

The chromium release test (CRT) was used to assess cell-mediated immunity to syngeneic, chemically-induced tumors in guinea pigs. The animal models were Sewall Wright strain 13 guinea pigs with 3-methyl-cholanthrene (MCA)-induced fibrosarcomas and strain 2 guinea pigs with diethylnitrosamine (DEN)-induced hepatocarcinomas. Regional lymph node cells were significantly cytolytic for the immunizing tumors, specifically so for three of the four tumors, and tumor-bearer sera could significantly block cytolysis. The two DEN-induced strain 2 hepatomas, line 1 and line 10, are antigenically distinct by the CRT but the two MCA-induced tumors have tumor specific antigens as well as a common, cross-reactive antigen.