Cytokines produced by innate immune response can profoundly influence the subsequent adaptive immunity. IL-15 and -18 are two of several mediators produced by macrophages that perform such a function. Here we present recent data mainly from our own laboratory illustrating the important role of IL-15 and -18 in the induction and perpetuation of chronic inflammation during experimental and clinical rheumatoid synovitis. (C) 2002 Elsevier Science Ltd. All rights reserved.