Identification and Localization of Human Pancreatic Tumor-associated Antigens by Monoclonal Antibodies to RWP-1 and RWP-2 Cells1

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 pro duction 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 P3x63/Ag8.653 were screened by enzymelinked immunosorbent assay for antibodies which reacted with both RWP-1 and RWP-2 cells. Hybridomas AR2-20 and AR128, both lgG1 antibody-producing cell lines, demonstrated mem brane 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 125l-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.