Expression of a Functional Laminin Receptor ( a 6 / 31 , very late activation antigen - 6 ) on Human Eosinophils

The mechanisms responsible for the accumulation of eosinophils at sites of allergic and other inflammatory reactions are unknown, but recent studies have implicated both eosinophil and endothelial adhesion molecules in this process. However, less well studied have been the adhesive interactions between eosinophils and the subendothelial basement membrane and interstitial connective tissues. To test the hypothesis that eosinophils might interact with extracellular matrix proteins, we analyzed purified human eosinophils for the expression and function of various B1 integrins. Using indirect immunofluorescence and flow cytometry, purified eosinophils from mildly allergic donors were found to consistently express the integrin subunits @1 (CD29). a4 (CD49d, very late activation antigen [VLA]-4a), and a6 (CD49f, VLA-6a). No significant expression of the a1 , a2, ~~3,015, or & subunits was detected. Platelet contamination of the eosinophil preparations was excluded by light microscopy and by the inability to detect expression of platelet glycoproteins av, CD41 b, and CD42b. Immunoprecipitation and sodium dodecyl sulfate-