Cutting edge: differential requirements for Stat4 in expression of glycosyltransferases responsible for selectin ligand formation in Th1 cells.

A role for Stat4 in IL-12-induced up-regulation of selectin ligands on Th1 cells was explored. Th1 cells generated from Stat4(-/-) mice exhibited no IL-12-inducible P-selectin ligands, no up-regulation of core 2 beta1,6-glucosaminyltransferase I (C2GlcNAcT-I), and low levels of the Th1 transcription factor T-bet. In contrast, Stat4(-/-) Th1 cells exhibited only a partial defect in expression of IL-12-inducible E-selectin ligands and expressed equivalently high levels of alpha1,3-fucosyltransferase VII (FucT-VII) as wild-type Th1 cells. FucT-VII expression was induced by T cell activation, and was enhanced by IL-12 independently of Stat4, whereas C2GlcNAcT-I up-regulation was mediated exclusively by IL-12, acting through Stat4. These data show that FucT-VII and C2GlcNAcT-I are controlled through distinct pathways and imply the existence of at least one other IL-12-inducible glycosyltransferase required for E-selectin and possibly P-selectin ligand formation in Th1 cells.