ENHANCED IN-VIVO IMMUNOGENICITY INDUCED BY AN ANTIBODY TO THE IL-4 RECEPTOR-ASSOCIATED GP200-MR6 MOLECULE

Four murine IgG1 monoclonal antibodies, each with specificity for a hu man tumour-associated antigen, have been tested for their in vivo immu nogenicity using a rabbit model. Surprisingly, one of these antibodies , MR6, was significantly more immunogenic than the remaining three rea gents. This enhanced MR6 immunogenicity was not restricted to the immu noglobulin molecule itself, but also applied to a hapten (fluorescein isothiocyanate, FITC) when conjugated to the monoclonal antibody. In a ddition, the secondary immune response to an independent antigen, huma n haemoglobin, was higher when the antigen was administered simultaneo usly with MR6 than when co-injected with an isotype-matched control mo noclonal antibody. The presence of the target antigen, gp200-MR6, on b oth rabbit and human leucocytes and epithelium, and its known associat ion with human IL-4 function, raises the possibility that antibody MR6 may not only target immunogens to antigen-presenting cells, but may a lso enhance the ability of these cells to present antigen to the immun e system. Antibodies to the gp200-MR6 may therefore find important cli nical application as in vivo adjuvants.