Histologic host response to primary methylcholanthrene-induced sarcomas in rats immunized with allogeneic tumors

Lymphocytic infiltration was observed in 44 of 51 (86%) 3-methylcholanthrene (MCA)-induced sarcomas in rats which had been intensively immunized with allogeneic tumors. Eleven of 29 (38%) tumors with intense lymphocytic infiltration and 5 of 15 (33%) tumors with moderate lymphocytic infiltration were "negative" in autologous transplantation. On the other hand, all of 7 tumors accompanied with slight or no lymphocytic infiltration were "positive".