In Situ Expression of Cytokines in Renal Cell Carcinoma

Abstract

Cytokines play an important role in the induction and maintenance of specific and nonspecific defense mechanisms by immunocompetent mononuclear cells in malignant tumors, including renal cell carcinoma (RCC) [1, 2]. Cytokines can directly or indirectly influence tumor cell growth and differentiation and are capable of influencing the expression of cell-surface antigens. While examining a series of RCC patients (n = 20) by means of immunocytochemistry with a polyclonal antibody to interleukin 6 (IL-6), we constantly observed positive reactions to IL-6 in tumor cells. Similar findings have been reported by other investigators in vitro [5, 8]. It has been suggested that IL-6 functions as an autocrine growth factor in RCC. Furthermore, in vitro experiments have shown that interleukin 4 alone or combined with interferon-γ (INF-γ) or tumor necrosis factor-α (TNF-α) inhibits tumor cell growth and modulates the expression of MHC class I and II antigens in RCC cells [6]. At present, however, only little information is available with respect to the expression of cytokines in RCC in situ. Therefore in a preliminary study we have analyzed the expression of selected cytokines and growth factors in a series of RCC patients by means of immunocytochemistry and molecular biology techniques.