Jeg-3 human choriocarcinoma-induced immunosuppression: Downregulation of interleukin-2, interleukin-2 receptor alpha-chain, and its Jak/Stat signaling pathway

PROBLEM: The mechanisms of the immunosuppressive and immunosuppression-indu cing capacities of Jeg-3 human choriocarcinoma cell line supernatants (HCSs ) are not yet completely understood. The influence on interleukin (IL)-2, I L-4 and interferon (IFN)-gamma production; IL-2 receptor (IL-2R) alpha-, be ta-, and gamma-chain; and the signaling pathway molecules Janus kinase (Jak )1, Jak3, signal transducers and activators of transcription (Stat)1, Stat3 , and Stat5 should be investigated. METHOD OF STUDY: For assessment of TL production, whole peripheral venous b lood from healthy donors was stimulated with phorbol-myrisrate-acetate and ionomycine. Secretion of ILs was blocked with monensine. Intracellular ILs were analyzed by flow cytometry. For IL-2R and signaling pathway molecule a nalysis, peripheral blood lymphocytes were stimulated with phytohemagglutin in (PHA). IL-2R chains were measured by flow cytometry, and Jaks/Stats by s odium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Wes tern blot. RESULTS: Phorbol-myristate-acetate and ionomycine strongly increase the per centage of IL-2(+) cells; an additional 50% HCSs significantly suppresses t he percentage to, or below the level of unstimulated cells. IFN-gamma produ ction is strongly decreased by HCSs in some cases. but not in others. PHA s timulates IL-2R alpha-, beta-, and gamma-chain expression and their signali ng pathway molecules Jak1, Jak3, Stat1, Stat3, and Stat5. 50% HCS downregul ates the alpha-chain and slightly upregulates the beta-chain. Jak1, Jak3, S tat1, Stat3, and Stat5 expression is suppressed approximately to, or below the level of unstimulated cells. CONCLUSIONS: HCS forcefully blocks the production of IL-2; the IL-2R alpha- chain; and Jak1, Jak3, Stat1, Stat3, and Stat5 expression. The observed phe nomena might be caused by downregulation of an IL-2R regulation gene, and m ight play a key role in the expansion of choriocarcinoma, and possibly in t he survival of the fetal allograft.