Interleukin 1 beta (IL1 beta) is a pro-inflammatory cytokine belonging to IL1 family. There are two known forms of IL1, IL1 alpha (predominant form in mice) and IL1 beta (predominant form in humans). IL1 beta and alpha are both synthesized as precursors. The IL1 beta precursor form is not biologically active, while IL1 alpha is. Expressed mainly by stimulated macrophages and monocytes, IL1 beta precursor is cleaved by Caspase 1/ICE and other proteases (2-3). Activated IL1 alpha remains mostly in the cytosol, activated IL1 beta is widely secreted. IL1 beta is known to be a mediator in inflammatory response and to be involved in a variety of cellular activities, proliferation, differentiation and apoptosis. Recent studies have shown IL1 beta to be a major cause of severe inflammation in the mouse model of Crohns disease, implicating IL1 beta as a potential marker for this disease (4).

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