Significance of soluble interleukin-2 receptor in patients with nasopharyngeal cancer

Background. In patients with nasopharyngeal cancer (NPC), titers of soluble interleukin-2 receptor (sIL-2R) increase following advancement of the disease. Because sIL-2R may induce immunosuppression, it is imperative to identify the source of sIL-2R. Methods. Concentrations of sIL-2R, sCD8, and antibody titer to Epstein-Barr virus (EBV) were measured by ELISA. Distribution of lymphocyte was characterized by immune histochemistry. Expression of IL-2R was studied by in situ hybridization. Results. High levels of sIL-2R and IgA to EBV were detected in patients with metastatic NPC. Levels of sCD8, however, did not follow the pattern of either IgA or sIL-2R. Message of sIL-2R was identified by in situ hybridization in part of cancer cells. Conclusion. High titer of IgA to EBV could be caused by the continuous exposure to EBV from epithelial origin. IgA to EBNA-1, ZEBRA, and EA-D suggests that EBV in NPC could be a mixture of active and latent infection. Levels of sIL-2R may correspond to the active expression of EBV gene in NPC. Expression of sIL-2R did not correlate with the lymphoid activity.