α(1,3) Fucosyltransferases IV and VII are essential for the initial recruitment of basophils in chronic allergic inflammation.

Basophils act as initiator cells for the development of IgE-mediated chronic allergic inflammation (IgE-CAI). However, detailed mechanisms of initial recruitment of basophils into the skin have yet to be clarified. Selectins mediate leukocyte capture and rolling on the vascular endothelium for extravasation. Counter-receptor activity of selectins is regulated by α(1, 3) fucosyltransferases (FTs) IV and VII. To clarify the contribution of selectin ligands regulated by FTs for initial basophil recruitment, IgE-CAI was induced in mice deficient in FT-IV and/or FT-VII genes. Although FT-IV(-/-) and FT-VII(-/-) mice exhibited comparable skin responses to wild-type mice, the FT-IV(-/-)/FT-VII(-/-) mice showed significantly impaired inflammation. Although the transfer of basophils to FcRγ(-/-) mice induced IgE-CAI, this induction was completely absent when basophils from FT-IV(-/-)/FT-VII(-/-) mice were transferred. L-selectin, but not P- and E-selectin, blocking Abs inhibited skin inflammation in vivo. P-selectin glycoprotein-1 (PSGL-1) antibody also ameliorated skin inflammation, and basophils were bound to L-selectin in a PSGL-1-dependent manner, which was regulated by FT-IV/VII. Functional PSGL-1 generated by basophil FT-IV/VII and its subsequent binding to L-selectin could be one of the essential steps required for initial basophil recruitment and the development of IgE-CAI in mice.