Feline Interleukin 1 Derived from Alveolar Macrophages Stimulated with Lipopolysaccharide

Abstract

The culture supernatants of feline alveolar macrophages stimulated with lipopolysaccharide (LPS) were found to have the ability to enhance mouse thymocyte proliferation in response to phytohemagglutinin A. None of these culture supernatants contained interleukin 2 (IL-2) activity, as determined by the murine IL-2 dependent T cell line (CTLL-2) cell proliferation assay. These results indicate that the thymocyte proliferation is attributed to feline interleukin 1 (IL-1). The maximal IL-1 activity was observed in the supernatants from alveolar macrophages cultured with LPS at concentrations ranging from 5 to 10μg/ml for 12hr. Feline IL-1 activity was sensitive to heat treatment at 70°C for 30min. The molecular weight (m. w.) of the feline IL-1 ranged from 15000 to 20000 daltons, as estimated by Sephacryl S-200 gel filtration, which was within the range of values estimated for IL-1 of humans, mice and rabbits. Feline IL-1 was eluted with three different isoelectric points of 4.1, 4.8 and 5.3, respectively, which resembles murine and human IL-1α.