The expression and biological activity of IL-2 receptor on a human pancreas cancer cell line

To ascertain whether the tumor cells can regulate the host immune systems through the production of the cytokines or their receptors, we examined the expressions of tumor necrosis factor alpha (TNF alpha), tumor necrosis factor beta (TNF beta), interleukin 2 (IL-2) and interleukin 2 receptor alpha chain (IL-2R alpha) on the human cancer cell lines by Northern blot analysis. We used K562 (leukemia cell line), MCF-7 (breast cancer cell line), LS180, HT29 (colon cancer cell lines), SH101 (gastric cancer cell line) and PH101 (pancreas cancer cell line). Expressions of TNF alpha, TNF beta and IL-2 mRNA were not detected in any of the tumor cell lines. However, 1.4 and 3.5 kilobases of the IL-2R alpha mRNA were expressed in the PH101 cells, but not in the other five cell lines. Furthermore, IL-2R alpha was detected on the cell surface of the PH101 cells by the flow-cytometric analysis with an anti-IL-2R alpha monoclonal antibody. Interestingly, the soluble IL-2R alpha (sIL-2R alpha) was found in the conditioned media obtained from the PH101 cell culture with a sandwich enzyme immunoassay. Moreover, the sIL-2R alpha secreted from the PH101 cells blocked the IL-2 dependent lymphocyte proliferation. These results indicate that the expression of IL-2R alpha on PH101 might suppress the IL-2 induced lymphocyte proliferation.