Molecular biology of interleukin-1

Interleukin-1 (IL-1) was first described more than a decade ago as lymphocyte-activating factor (LAF) for its ability to costimulate mitogen-activated mouse thy-mocyte proliferation (Gery et al. 1971). Since this ini-tial observation, it has become clear that IL-1 has a number of other biological activities and that there are at least two major types of IL-1 proteins produced by activated macrophages and by other cell types. Some of the activities ascribed to IL-1 include the ability to stimulate B-cell function, fibroblast proliferation, muscle proteolysis, prostaglandin E2 (PGE2) and col-lagenase production by rheumatoid synovial cells, he-patic acute-phase protein synthesis, and to induce fever (for review, see Dinarello 1984). Although its activities are numerous and diverse, it has been suggested tha