High Serum and Ascitic Soluble Interleukin-2 Receptor α Levels in Advanced Epithelial Ovarian Cancer

Abstract

AbstractThis study was undertaken to determine if advanced epithelial ovarian cancer was associated with increased serum and ascitic levels of soluble interleukin-2 receptor α (sIL-2Rα). Serum and ascitic fluid samples from 23 ovarian cancer patients were analyzed for slL-2Rα using an enzyme-linked immunosorbent assay and compared with the serum and peritoneal levels in 18 normal females. The samples were analyzed for CA-125 levels using a radioimmunoassay and the total protein was also measured. Normal individuals had low serum levels of slL-2Rα (367.5 ± 44.6 U/mL), with similar levels of slL-2Rα in the normal peritoneal fluid (438.6 ± 48.8 U/mL). In contrast, the serum and ascitic fluid levels in ovarian cancer patients were significantly higher (746.7 ± 82.9 U/mL, P = .0006; 2,656.7 ± 373.7 U/mL, P = .00002, respectively). The results for slL-2Rα were also significant when the levels were expressed per milligram of total protein. More importantly, in almost every ovarian cancer patient the ascitic slL-2Rα level far exceeded the serum level, a pattern also observed for CA-125. There was no correlation between the serum and ascitic slL-2Rα levels, or between the serum and ascitic CA-125 levels. Although the serum levels of slL-2Rα and CA-125 were elevated in the same patient, overall there was no correlation between the serum slL-2Rα and serum CA-125 levels, either when the levels were expressed in absolute units or per milligram of total protein. Similarly, there was no correlation between slL-2Rα and CA-125 levels in individual ascitic samples. While CA-125 levels may reflect an independent index of tumor burden, these results suggest that selective accumulation of slL-2Rα in the ascites may be one of the factors associated with the known nonresponsiveness of the infiltrating lymphocytes against ovarian carcinoma cells.