FUNCTIONAL-CHARACTERIZATION OF RAT CHEMOKINE MACROPHAGE INFLAMMATORY PROTEIN-2

Expression of mRNA for the C-X-C chemokine, macrophage inflammatory pr otein-2 (MIP-2), is induced during acute inflammation in rat models of disease. We have characterized the phlogistic potential of rat recomb inant MIP-2 (rMIP-2) protein in vitro and in vivo. Recombinant MIP-2 c aused marked PMN chemotaxis in vitro, with peak chemotactic activity a t 10 nM. Incubation of whole blood with rMIP-2 caused a significant lo ss of L-selectin and a significant increase in Mac-1 expression on the PMN surface. Under similar conditions rMIP-2 also caused a modest res piratory burst in PMNs. The intratracheal instillation of 10 and 50 mu g of rMIP-2 caused a significant influx of PMNs into the airspace of the lungs. Rat MIP-2 is a potent neutrophil chemotactic factor capable of causing neutrophil activation and is likely to function in PMN rec ruitment during acute inflammation in rat disease models.