Therapy of the of the Immune

ABSTRACT-The murine plasmacytoma MOPC 104E was sus-ceptible to cytotoxic therapy In female Inbred BALB/c mice. Palpable subcutaneous tumors (0.6-1.2X10 · cells) could be cured with a single administration of cyclophosphamide (5-250 mg/kg) or localized Irradiation (800-2,400 R). Clonogenlc assay showed that, following minimal curative doses of cyclophosphamide or radiation, 0.5-1.5X10 · tumor cells should remain viable. Control animals succumbed to progressive, invariably lethal tumor growth after they were given sc Injections of 2-3x10 ' tumor cells. Minimal doses of cyclophosphamide, which were curative in control tumor-bearing animals, were ineffective In treating tumor-bearing animals immunosuppressed by 450 R whole-body Irradia-tion. Subsequent experiments measured the ability of animals cured of the murine plasmacytoma to reject secondary challenge with the same tumor. These experiments demonstrated an