IL-1 Charles A. Dinarello* Department of Infectious Diseases, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, B168, Denver, CO 80262, USA * corresponding author tel: 303-315-3589, fax: 303-315-8054, e-mail:
[email protected] DOI: 10.1006/rcwy.2000.04001. SUMMARY IL-1 is distinct from the other agonist member of the IL-1 family, IL-1 . Although IL-1 triggers the same IL-1 receptor and although many of the biological effects of IL-1 are similar to those of IL-1 , in humans IL-1 is predominantly an intracellular molecule. In fact, there is evidence that IL-1 has both intracellular functions as a precursor molecule due to a nuclear localization sequence. IL1 as an unprocessed precursor is biologically as active as the processed form. IL-1 is also found consitutively in epithelial cells, whereas constitutive expression of IL-1 is rare. In many ways, IL-1 appear