CHARACTERIZATION OF INFLUENZA-A VIRUS BINDING-SITES ON HUMAN NEUTROPHILS

Exposure of human neutrophils (PMN) to influenza A virus (IAV) trigger s discrete responses in these cells that interfere with their normal h ost defense functions. Because the restricted host range and tissue sp ecificities of many viruses are determined by cell surface molecules a cting as virus receptors on target cells, it seemed plausible that IAV might interact with neutrophils via specific plasma membrane glycopro teins that bind to viral hemagglutinin. When the binding of intact IAV (ATCC strain A/PR/8/34 (H1N1)) to PMNs was examined by flow cytometry , virus binding was found to be saturable and to be diminished after e xtensive desialation of the cells with neuraminidase. Stimulation of P MNs with FMLP (0.1 mu M) caused a transient increase in IAV binding th at was maximal (>200%) at 2 min after stimulation. When neutrophil mem brane proteins were separated by gel electrophoresis and transferred t o nitrocellulose, IAV bound selectively to two polypeptide bands of ap proximately 125 and 160 kDa. Relative binding to these two bands was m odified and ultimately eliminated by treatment of PMN membrane protein s with neuraminidase before electrophoresis and blotting. Intact virus precipitated a limited number of proteins from solubilized PMN plasma membrane preparations, and Abs specific for sialophorin (CD43) recogn ized virus-precipitated PMN membrane proteins of the same apparent m.w . as those detected in virus-membrane protein blots. These findings in dicate that IAV binds to human PMNs through interactions with a limite d number of PMN membrane glycoproteins, which include sialophorin (CD4 3).