Chemotactic cytokines: the role of leukocytic pyrogen and epidermal cell thymocyte-activating factor in neutrophil chemotaxis.

Macrophage-derived leukocytic pyrogen (LP) is thought to be similar if not identical to interleukin 1 (IL 1). In addition to macrophages, keratinocytes produce a factor that has similar biologic and biochemical characteristics to IL 1, called epidermal cell thymocyte-activating factor (ETAF). Because many diseases affecting the skin are characterized by infiltration of polymorphonuclear leukocytes (PMN) and some of these disorders are associated with fever, we investigated whether ETAF like LP had pyrogenic activity, and whether ETAF or LP were chemoattractants. ETAF or LP purified by column chromatography and isoelectric focusing were found to have chemotactic activity for PMN. The fractions containing maximal chemotactic activity corresponded to maximal fever-inducing activity and maximum thymocyte-activating activity. Furthermore, the chemotactic activity of ETAF and LP could be blocked by an antibody directed against LP. The results of this study indicate that these mediators, which arise from distinct cell populations, are closely related and may play a vital role in skin as well as distant inflammatory and immunologic events.