Cell locomotion is crucial to the induction of an effective immune response. We report here the chemoattraction of CD4� T cells
by IL-18, a member of the IL-1 cytokine family. Recombinant IL-18 increased the proportion of T cells in polarized morphology
in vitro and stimulated their subsequent invasion into collagen gels in an IL-18 concentration gradient-dependent manner. Immunofluorescent
microscopy studies determined that the major cell type responding to IL-18 was IL-18R�CD4�. Importantly,
synovial CD4� T cells from patients with rheumatoid arthritis responded to IL-18, adopting polarized morphology and gel
invasion without further activation ex vivo, indicating the physiologic relevance of our observations. Finally, injection of rIL-18
into the footpad of DBA/1 mice led to local accumulation of inflammatory cells. These data therefore demonstrate for the first time
lymphocyte chemoattractant properties of a member of the IL-1 cytokine family and its relevance in inflammatory disease
