CLONING OF RAT EOTAXIN - OZONE INHALATION INCREASES MESSENGER-RNA ANDPROTEIN EXPRESSION IN LUNGS OF BROWN-NORWAY RATS

The C-C chemokine eotaxin is thought to be important in the selective recruitment of eosinophils to the site of inflammation in guinea pigs, mice, and humans. We isolated the rat eotaxin gene to determine wheth er a similar molecule might play a role in the pulmonary infiltration of eosinophils during acute inflammation in the rat. The cDNA for rat eotaxin encoded a 97-amino acid protein containing a 74-amino acid mat ure eotaxin protein with 97.3% identity to mouse eotaxin. The recombin ant protein encoded by this gene displayed specific chemotactic activi ty for eosinophils when analyzed with a microchemotactic chamber. The expression of eotaxin mRNA increased similar to 1.6-fold immediately a fter exposure to ozone and was 4-fold higher after 20 h. The number of lavageable eosinophils at the same time points were 3- and 15-fold gr eater, respectively, than control eosinophils. Immunocytochemistry rev ealed that alveolar macrophages and bronchial epithelial cells were po sitive for eotaxin. These results suggest that eotaxin may be involved in the recruitment of eosinophils into the air spaces during certain inflammatory conditions in rats.