INCREASED EXPRESSION OF THE MONOCYTE CHEMOATTRACTANT PROTEIN-1 IN BRONCHIAL TISSUE FROM ASTHMATIC SUBJECTS

The expression of the monocyte chemoattractant protein (MCP-1), a memb er of the chemokine family of low molecular weight cytokines, was asse ssed by immunohistochemistry in bronchial biopsies from 12 asthmatic a nd 12 normal subjects. Both a monoclonal antibody (F9) and a polyclona l antibody were employed to detect MCP-1, while the mouse myeloma prot ein (MOPC21) was used as a negative control. Strong positive reactions for MCP-1 were seen in the bronchial epithelium. Subepithelial macrop hages, blood vessels, and bronchial smooth muscle were also stained. H ue-saturation-intensity color image analysis was used to quantify reac tions of the monoclonal antibody in the epithelial and subepithelial l ayers. With the monoclonal antibody, asthmatic biopsies showed 51.8 +/ - 3.7% (mean +/- SEM) of the epithelium staining positively, whereas n ormal subjects reacted much less, with 6.4 +/- 1.9% of the epithelium staining (P < 0.0001); there was no overlap between the two groups. Li kewise, staining was increased in the subepithelium of asthmatic airwa y biopsies, with 11.5 +/- 3.1% and 2.0 +/- 1.0% staining positively in asthmatic and normal subepithelium, respectively, (P < 0.002). There was a significant correlation between staining of the epithelium and s ubepithelium (r = 0.77, P < 0.001). The polyclonal anti-MCP-1 antibody also gave strong reactions in the epithelium and subepithelium, with 34.0 +/- 7.8% of the asthmatic and 1.6 +/- 1.0% of the normal bronchia l epithelium staining positively (P < 0.0001). These increased levels of MCP-1 in the asthmatic airways suggest that they may play a role in macrophage recruitment and activation and thereby contribute to the i nflammatory pathology of bronchial asthma.