Rat CINC, a member of the interleukin-8 family, is a neutrophil-specific chemoattractant in vivo.

Rat cytokine-induced neutrophil chemoattractant (CINC) is a member of the IL-8 family and its human counterpart is MGSA/gro. Rat neutrophil responses in vitro to rat CINC, human IL-8, and human MGSA/gro were studied. CINC concentrations as low as 1 nM induced apparent chemotaxis of rat neutrophils, but human IL-8 and MGSA/gro required concentrations one or two orders higher than that of CINC to attract neutrophils. These data indicate that human IL-8 and MGSA/gro cannot sufficiently substitute for rat counterparts such as CINC in rats. Therefore, the effect of rat CINC on rats was studied. Intradermally injected 10(-10)-10(-7) M CINC dose-dependently caused infiltration of neutrophils. Significant migration of neutrophils appeared by 30 min, and maximum infiltration was observed around 1-2 hr after the injection. CINC induced quick and transient neutrophil accumulation without lymphocyte and monocyte migration or edema formation. CINC, a member of the IL-8 family but a counterpart of human MGSA/gro-related proteins, is a specific neutrophil chemoattractant and can be distinguished from IL-8, which is a chemotactic factor for lymphocytes and neutrophils.