The beta form is the dominant interleukin 1 released by murine peritoneal macrophages.

Using highly specific polyclonal antisera raised against recombinant murine IL-1 alpha and beta, we performed solid-phase immunoabsorption studies on supernates of resident and adjuvant-elicited CBA/J mouse peritoneal macrophages. Antibody specificity was established by reciprocal absorption studies and Western blot analysis. Supernates obtained from macrophages cultured for 18 hr in the presence of 1 microgram/ml lipopolysaccharide (LPS) were subjected to immunoabsorption. Approximately 78-90% of the released bioactive material was IL-1 and about 80% of this could be attributed to IL-1 beta. Analogous to that reported for human monocytes, these data suggest that IL-1 beta is the predominant released form of IL-1.