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Regulation of fucosyltransferase‐VII expression in peripheral lymph node high endothelial venules

Binding of L‐selectin to the highly glycosylated peripheral lymph node addressins (PNAd) plays a central role in the normal recirculation of lymphocytes between the bloodstream and the lymph node. This interaction requires correct fucosylation of the PNAd, mediated by the recently identified fucosyltransferase‐VII (Fuc‐TVII). Here we show that during ontogeny Fuc‐TVII is absent at the day of birth, barely detectable on day 1, and clearly present from day 2 onwards. PNAd expression as detected by the MECA‐79 antibody precedes the expression of Fuc‐TVII. Furthermore, we demonstrate that in adult mice antigenic stimulation of peripheral lymph nodes leads to a temporary disappearance of Fuc‐TVII at days 2 and 3 after stimulation, followed by a complete reappearance by day 4, while expression of MECA‐79 is never completely absent during this period. Finally, occlusion of afferent lymphatics to peripheral lymph nodes resulted in a decreased expression of Fuc‐TVII in the high endothelial venules by day 5, and complete disappearance within 8 days. We conclude that the activity of Fuc‐TVII in cells of high endothelial venules is directly affected by afferent lymph and activation processes that occur in the lymph node after antigenic stimulation. The expression of Fuc‐TVII is therefore yet another level at which the function of high endothelial venules, and thus lymphocyte trafficking, can be regulated.