THE PRODUCTION OF INTERLEUKIN-1 RECEPTOR ANTAGONIST BY HUMAN BRONCHOGENIC-CARCINOMA

Bronchogenic carcinoma displays an aggressive clinical course that may reflect a capacity to evade host defenses. We postulated that tumors may elaborate interleukin-1 receptor antagonist protein (IRAP) to esca pe host interleukin-1-dependent responses. Homogenates of human bronch ogenic lung tumors demonstrated significant increases of IRAP compared with normal lung tissue controls (n = 48). There was no significant d ifference in interleukin-1beta levels between tumor and normal lung ti ssue. Immunohistochemical staining localized IRAP to tumor cells. Semi quantitative pathological analysis demonstrated a modest inflammatory cell infiltrate with qualitative differences between tumors of differe nt histology. Western blot analysis of tumor homogenates demonstrated several molecular weight forms of IRAP. Finally, antigenic IRAP was de tected in supernatants of the human bronchogenic carcinoma cell line ( A549) maintained in vitro. These findings illustrate the capacity of b ronchogenic tumors to produce and secrete IRAP that may be important i n tumor evasion of host defenses.