INTERLEUKIN-8 EXPRESSION BY HEAD AND NECK SQUAMOUS-CELL CARCINOMA

Objective: To test the hypothesis that interleukin-8 (IL-8) is produce d by human head and neck squamous cell carcinomas (HNSCCAs) and may th erefore be a possible mediator for lymphocyte recruitment and neovascu larization by these tumors. Methods: Nine fresh samples of HNSCCA were analyzed for expression of IL-8 antigen using radioimmunoassay and im munohistochemical staining techniques. Also, four short-term primary c ultures of HNSCCA and two continuous HNSCCA cell lines were then analy zed for production of IL-8 expression under both baseline conditions a nd following stimulation with other cytokines. Results: The IL-8 antig en was detected in all fresh tumor homogenates by radioimmunoassay (5. 58 to 331.69 ng of IL-8 per gram of tissue), and immunohistochemical r esults localized staining predominantly within the tumor cells. Primar y cultures of HNSCCA and continuous HNSCCA cell lines produced only lo w levels of IL-8 (0.04 to 4.49 ng of IL-8 per 10(6) cells) under basel ine (unstimulated) conditions. Stimulation of both primary cultures an d cell lines with interleukin-1 and tumor necrosis factor induced sign ificant increases in IL-8 antigen, while other cytokines failed to ind uce a significant increase. Conclusions: This study demonstrates that IL-8 antigen is expressed by HNSCCA in vivo, and that cultured HNSCCA in vitro can be stimulated to express IL-8 antigen by both interIeukin -1 and tumor necrosis factor. local production of IL-8 by HNSCCA cells , and its regulation by other cytokines, may be important in both the lymphocyte recruitment and tumor neovascularization seen in HNSCCA, an d may thus ultimately affect the natural history of the disease.