REPORTS Enhanced Expression of Interleukin-6 in Primary

We have demonstrated interleukin-6 (IL-6) production by human renal car-cinoma cells. The IL-6 gene expression was detected by Northern blot analysis in 22 of 43 primary renal cell carcinoma tissues and in five of seven renal cell car-cinoma cell lines. Immunohistochemical analysis confirmed the expression of IL-6 by the tumor cells. Patients with a high-level expression of IL-6 had significantly greater incidences of lymph node metas-tasis and a larger increase in serum C-reactive protein than those without it. We have also probed for the presence of IL-6 receptor by Northern blot analysis; we detected this receptor in 11 of the 43 primary renal cell carcinoma tissues but in none of the seven renal cell carcinoma cell lines. However, by use of the com-plementary DNA-polymerase chain re-action, the IL-6 receptor transcript was detected in all specimens, including the seven cell lines. No expression of the in-terleukin-3 (IL-3) gene was identified in any of the 43 primary renal cell tumors. These data provide evidence that IL-6 and its receptor may play a role in promoting the transformation and/or proliferation of renal cell carcinomas as well as in the development of symptoms