REGULATION OF FUCOSYL-TRANSFERASE-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 interact ion requires correct fucosylation of the PNAd, mediated by the recentl y identified fucosyltransferase-VII (Fuc-TVII). Here we show that duri ng 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 d etected by the MECA-79 antibody precedes the expression of Fuc-TVII. F urthermore, 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 reappearanc e by day 4, while expression of MECA-79 is never completely absent dur ing this period. Finally, occlusion of afferent lymphatics to peripher al lymph nodes resulted in a decreased expression of Fuc-TVII in the h igh endothelial venules by day 5, and complete disappearance within 8 days. We conclude that the activity of Fuc-TVII in cells of high endot helial venules is directly affected by afferent lymph and activation p rocesses that occur in the lymph node after antigenic stimulation. The expression of Fuc-TVII is therefore yet another level at which the fu nction of high endothelial venules, and thus lymphocyte trafficking, c an be regulated.