Identification and localization of human pancreatic tumor-associated antigens by monoclonal antibodies to RWP-1 and RWP-2 cells.

Human pancreatic adenocarcinoma cell lines, RWP-1 and RWP-2 (Dexter, D. L., Matook, G. M., Meitner, P. A., Bogaars, H. A., Jolly, G. A., Turner, M. D., and Calabresi, P. Cancer Res., 42: 2705-2714, 1982), were used as immunogens for the production of monoclonal antibodies to tumor-associated membrane antigens. BALB/c mice were immunized by i.p. injection of viable cells and hybridomas resulting from the fusion of splenocytes to myeloma cell line P3 X 63/Ag8.653 were screened by enzyme-linked immunosorbent assay for antibodies which reacted with both RWP-1 and RWP-2 cells. Hybridomas AR2-20 and AR1-28, both IgG1 antibody-producing cell lines, demonstrated membrane staining by immunofluorescence cytochemistry on three of seven pancreatic tumor cell lines but not on six human tumor cell lines of nonpancreatic origin, or on normal human fibroblasts. The antibodies stained frozen sections of RWP xenografts, propagated s.c. in nude mice, and tumor cells in paraffin sections of seven of seven cases of pancreatic ductal adenocarcinoma, using indirect immunofluorescence and immunoperoxidase histochemistry, but not normal adult or fetal pancreas, or a number of other normal adult tissues. Immunoprecipitation of 125I-labeled RWP-2 cells resulted in a single band with a molecular weight of 190,000 under reducing conditions. Sequential immunoprecipitation demonstrated that both AR2-20 and AR1-28 bind to the same molecule.