Role of the spleen on immunosuppression in esophageal and gastric cancer.

To elucidate the role of the spleen on immunosuppression of gastric and esophageal cancer, suppressor cell activities of spleen cells (SCs), splenic vein lymphocytes (SVLs) and peripheral blood lymphocytes (PBLs) were investigated. Concanavalin-A induced suppressor cell (Con-AS) activity of SCs was significantly higher in patients with gastric cancer than in those with benign diseases. Higher Con-AS activity of SCs was observed in esophageal cancer patients with tumors located in the lower portion of the esophagus. In comparison with suppressor activities of SCs and SVLs, the decrease of the predominance of suppressor precursors in SCs and the increase of the spontaneously activated suppressor cells in SVLs were noted with the advance of the tumors. Culture supernatants from splenic adherent cells significantly induced suppressor cell activities as well as did sera from splenic venous blood. From these results, it is concluded that the generation of suppressor precursors in the spleen is dependent on the location of tumors and that the maturation of suppressor cells occurs in the spleen by factors released from splenic adherent cells, then migrates into the peripheral blood.