The ALF-161 monoclonal antibody reacts with precursor, secreted and membrane-associated forms of mouse IL-1α (interleukin 1 alpha) also known as lymphocyte activating factor (LAF), and mononuclear cell factor (MCF). IL-1α is a 17 kDa pro-inflammatory cytokine produced by a variety of cells, including macrophages, dendritic cells, T and B lymphocytes. IL-1α exerts a wide range of immune and inflammatory responses on a many cell types including lymphocytes, epithelial cells and fibroblasts. IL-1 is made up of IL-1α and IL-1β which are the products of distinct genes, but which are recognized by two distinct IL-1 receptors. The IL-1 receptor type I, a 80 kDa transmembrane protein with demonstrated IL-1 signaling function and the IL-1 receptor type II, a 68 kDa membrane protein with a relatively short cytoplasmic tail. The type II receptor acts as a decoy target for IL-1, inhibiting IL-1 activities by preventing the binding of IL-1 to the type I receptor. The ALF-161 antibody has been shown to neutralize the bioactivity of natural or recombinant IL-1α.