The lymphocyte response to a primary viral neoplasm (MSV) through its entire course in BALB/c mice

BALB/c mice injected with Moloney sarcoma virus (MSV) developed tumors within 5–8 days which usually completely regressed by day 20–25. Maximal tumor size was around day 15. Lymphocytes from these animals were examined for activity against target cells bearing the Moloney leukemia virus (MLV) associated cell surface antigen at 2‐ to 5‐day intervals for 30 days. Significantly cytotoxic lymphocytes were obtained from animals which had developed no palpable tumor as early as 2 days after infection and from animals in which tumors had completely regressed. The least active lymphocytes were from tumor‐bearing animals. The cytotoxicity of the active lymphocytes was demonstrated to be antigen‐specific by testing also against target cells which were MLV‐negative.