IL-1 refers to two proteins, IL-1alpha and IL-1beta which are the products of distinct genes, but which are recognized by the same cell surface receptors. IL-1beta is a potent immuno-modulator which mediates a wide range of immune and inflammatory responses including the activation of B and T cells. The B122 antibody reacts with the precursor and mature secreted forms of mouse IL-1beta. This antibody also recognizes rat IL-1beta. The B122 antibody can neutralize the bioactivity of natural or recombinant IL-1beta.