COMMENTARY Blood, sweat, and chemotactic cytokines

Cytokine actions can be physiological, pharmacological, or toxic, depending on the concentration that is available and the cell type and host organism studied. Because they oper-ate in vivo in complex networks, the salutary functions of any one cytokine can sometimes be difficult to pin down. Such has been the case for interleukin-8 (IL-8) and related members of the family of chemotactic cytokines or chemokines that are best known for their powerful effects on blood leukocytes [1]. Instead, considerable evidence from animal studies has incriminated IL-8 as a major mediator of acute, neutrophil-dependent inflammatory pathology [2]. Other chemokines have also been implicated in inflamma-tory injury, although the demonstration of guilt is thus far by association. It stands to reason, however, that chemokines exist for rca