Interleukin-1α activation and localization in lipopolysaccharide-stimulated human monocytes and macrophages

Background: Interleukin-1α (IL-1α) is a proinflammatory cytokine belonging to the IL-1 family. It is synthesized as a 33 kDa precursor peptide that is cleaved by a calpain-like protease to a 16 kDa propiece and a 17 kDa mature IL-1α peptide. In contrast to its close relative, IL-1β, the role of IL- 1α in inflammation is only partly understood.

Results: Human macrophages/monocytes, stimulated with lipopolysaccharide (LPS) were analyzed for production and localization of IL-1α by use of a monoclonal antibody (MAb) generated against IL-1α pro piece. We found that IL-1α propiece was detected within the nuclei of the cells 2 hours (hrs) after LPS stimulation and production continued for up to 20 hrs. The MAb was conjugated to fluorescein isothiocyanate (FITC) for use in flow cytometry. Based on the flow cytometric analysis CD68 positive cells were positive for IL-1α in agreement with CD68 being a marker for monocytes.

Conclusions: Here, we demonstrate, for the first time, a method to visualize and measure the production of IL-1α in both human monocytes and macrophages.