IL2 and neoplasm: To confirm our hypothesis that host T cells play little or no role in tumor regression after adoptive transfer, athymic nude mice with 4 day 4T1 tumors were treated with CYP alone or CYP + B/I activated 4T1 draining lymphocytes, with or without exogenous IL-2 (7500 U i.p. on days 0 - 3 after AIT).