The ability of Legionella pneumophila to induce secreted IL-1 (sIL-1) and membrane associated IL-1 (mIL-1) in murine peritoneal, splenic, and pulmonary macrophages was examined. Two preparations of L. pneumophila were utilized, specifically, a formalin-killed, whole-cell preparation and viable bacteria. We demonstrated that both forms induce mIL-1 and sIL-1 in each of the macrophage populations tested; however, there were differences in the magnitude of responses with the different macrophage populations. In general, the viable bacteria induced greater IL-1 activity than did equivalent numbers of formalin-killed bacteria, with the exception of the highest concentrations tested (10(7) bacteria/ml). The results demonstrate that L. pneumophila induces production of both sIL-1 and mIL-1 activities by murine macrophages from a variety of tissues.