Characterization of a novel immunocytolytic factor secreted by pancreatic adenocarcinoma

We observed a putative immunocytolytic factor secreted in the supernatant o f several pancreatic adenocarcinoma cell lines that induces apoptosis in ly mphocytes, A marked reduction in the viability of the target splenocytes wa s evident after coincubation with the supernatants from various pancreatic adenocarcinoma cell lines (human, hamster, and murine). The immunocytolytic effect was not evident with the conditioned media of normal pancreatic duc t epithelial cells or other nonpancreatic tumor cells. Biologic activity of the supernatants was determined to be heat sensitive and reside in a 30- t o 50-kDa range. Immune and functional assays have excluded known immunosupp ressive factors.