Abstract
Immunotherapy using rat 7s antibodies against plasmacytoma 5563 in C3H mice has been measured carefully. Prior adsorption of antibodies with normal mouse tissues, and supplements of co-optable non-immunized macrophages and lymphocytes enhanced the scope of immunotherapy against established tumours. It is suggested that available co-optable lymphocytes and macrophages are imporant limiting factors in tumour immunotherapy.