IL-1beta is a proinflammatory cytokine produced in a variety of cells including monocytes，tissue macrophages，keratinocytes and other epithelial cells. Both IL-1alpha and IL-1beta binds to the same receptor and has similar if not identical biological properties. These cytokines have a broad range of activities including，stimulation of thymocyte proliferation，by inducing IL-2 release，B-cell maturation and proliferation，mitogenic FGF-like activity and the ability to stimulate the release of prostaglandin and collagenase from synovial cells. However，whereas IL-1beta is a secreted cytokine，IL-1alpha is predominantly a cell-associated cytokine. Recombinant murine IL-1beta is a 17.5 kDa protein containing 153 amino acid residues.
