INTERLEUKIN-8 AND MONOCYTE CHEMOATTRACTANT PROTEIN-1 MESSENGER-RNAS IN OXYGEN-INJURED RABBIT LUNG

The chemokines interleukin-8 (IL-8) and monocyte chemoattractant prote in-1 (MCP-1) are neutrophil and monocyte attractants, respectively. We hypothesized that IL-8 and MCP-1 mRNA expression in alveolar macropha ges (AM) lavaged from rabbit lung would be increased by oxygen exposur e, which is known to induce inflammation. Adult rabbits were exposed t o >95% oxygen for up to 64 h and allowed to recover in room air for up to 72 h before killing and pulmonary lavage. Numbers of lavageable po lymorphonuclear cells (PMN) and AM rose during the exposure protocol. Quantitative in situ hybridization with H-3-labeled cRNA probes showed both IL-8 and MCP-1 mRNA expression in AM during oxygen exposure, wit h peak levels of IL-8 mRNA at 56-h oxygen exposure and of MCP-1 mRNA a t 64-h oxygen exposure with 24-h room air recovery. IL-8 mRNA was pres ent in PMN between 48-h oxygen exposure and 64-h oxygen exposure with 24-h room air recovery. MCP-1 mRNA was not expressed in PMN. This patt ern of chemokine mRNA expression emphasizes the importance of inflamma tory cells as effecters in the pulmonary response to oxygen exposure.