Production and in vivo characterization of a bifunctional antibody (IVA039.1) with specificity for the mouse interleukin-2 receptor and vinca alkaloids.

The autoreactive T cell plays a pivotal role in the pathogenesis of type I diabetes in humans and in rodent animal models. Elimination or attenuation of these cells may provide a means to treat the disease. The use of antibodies directed to T cells has shown varying degrees of effectiveness in the treatment of autoimmune disease. The use of a bifunctional antibody directed to T cells with a cytolytic agent may provide an additional level of therapeutic efficacy compared to anti-T-cell antibodies alone. To test this hypothesis, we prepared a bifunctional antibody (IVA039.1) with specificity for the mouse interleukin-2 (IL-2) receptor and vinca alkaloids. The antibody was derived from the fusion of vinca immune spleen cells with PC61 5.3, a hybridoma that produces rat anti-mouse IL-2 receptor antibody. IVA039.1 was purified by affinity chromatography through Protein A and anti-vinca affinity columns followed by TSK-DEAE high-pressure liquid chromatography (HPLC). Bifunctionality of the antibody was confirmed by fluorescence-activated cell sorting (FACS) analysis, enzyme-linked immunoadsorbent assay (ELISA) and a cell assay designed to measure simultaneously both IL-2 receptor and vinca reactivities. The biodistribution of IVA039.1 was determined in normal and streptozotocin-complete Freund's adjuvant (CFA) induced diabetic mice. Enhanced uptake of IVA039.1 was observed in the pancreata, spleens, and lymph nodes of diabetic compared to normal mice. These data suggest that bifunctional antibodies that can deliver cytolytic agents to T cells may be appropriate candidates for the treatment of diabetes and other autoimmune diseases.