SERUM-SOLUBLE INTERLEUKIN-2 RECEPTOR AND IMMUNOHISTOCHEMICAL STAININGOF IL-2R TAC ANTIGEN IN GASTRIC-CANCER/

In the present study, we investigated the significance of serum solubl e IL-2R as a tumor marker, and examined the existence and localization of positive cells for IL-2R/Tac antigen in gastric cancer tissues and its regional lymph nodes. Eighty-two patients with gastric cancer wer e included. Levels of serum soluble-IL-2R were measured by an enzyme-l inked immunosorbent assay. In the tissues obtained from 19 cases, immu nohistochemical staining was performed with the use of avidin-biotin-p eroxidase complex technique, in which mouse anti-human interleukin-2 r eceptor antibody was used. The preoperative levels of serum soluble IL -2R in patients-with gastric cancer were significantly higher than tho se of normal controls (p<0.001). The levels of serum soluble IL-2R in cases with metastatic lymph nodes were also significantly higher than those without metastatic lymph nodes (p<0.05). Concerning the tumor ma rkers, there were significant differences of serum soluble IL-2R level s between those who were positive and those negative for CA19-9, CEA, alpha-FTP, and IAP. In the immunohistochemical staining of IL-2R, 13 o f 19 cases (68.4%) showed IL-2R positive cells in the gastric cancer t issues. In regard to the metastatic lymph nodes, 3 of 5 cases (60.0%) showed IL-2R positive cells. On the other hand, IL-2R positive cells w ere not recognized in normal gastric tissues and non-metastatic lymph nodes. These results may suggest that activated T-lymphocytes infiltra ting into the cancer tissues play an antitumor role and release a larg e amount of alpha-chain of IL-2R, resulting in the high levels of seru m soluble IL-2R in patients with gastric cancer.