Preliminary experience in treating lymphocytic leukaemia with antibody to immunoglobulin idiotypes on the cell surfaces.

Tumour-specific antiserum was raised in sheep against idiotypic determinants on the surface immunoglobulin of neoplastic lymphocytes from a patient with chronic lymphocytic leukaemia (prolymphocytic variant). The complement-activating IgG1 subclass of the anti-idiotype was prepared from the serum in monodisperse form for infusion. Two treatments of 480 and 1200 mg caused the white-cell count to fall by one-third and one-half respectively. However, there was a rapid resurgence, so that by 8 days after each treatment the counts were restored to approximately 85% of their former levels. No change was noted in the size of spleen or lymph nodes. Each treatment probably destroyed 4-8 X 10(11) cells, some 10% of the total tumour load. The antibody was rapidly consumed, and there was evidence of heavy utilization of complement.