Syndecan-4 as antithrombin receptor of human neutrophils

Antithrombin inhibits chemokine-induced migration of neutrophils by activat ing heparan sulfate proteoglycan-dependent signaling. Mechanisms of antithr ombin's effects on neutrophils were, therefore, studied by testing function and expression of heparan sulfate proteoglycans in RT-PCR or flow cytometr y and cell migration assays, respectively. In vitro effects of antithrombin on human neutrophil migration in modified Boyden chambers were abolished b y pretreating cells with heparinase-1, chondroitinase, sodium chlorate, and anti-syndecan-4 antibodies. Expression of syndecan-4 mRNA and protein in n eutrophils was demonstrated in RT-PCR and anti-syndecan-4 immunoreactivity assay, respectively. In the presence of pentasaccharide, antithrombin lost its activity on the cells. Data suggest that antithrombin regulates neutrop hil migration via effects of its heparin-binding site on cell surface synde can-4. (C) 2001 Academic Press.