The selective expression of distinct fucosylated glycoproteins on murine T and B lymphocyte subsets

Abstract

The putative expression of distinct terminally fucosylated glycoconjugates among murine lymphocyte subpopulations was sought using Ulex europaeus agglutinin-I (UEA-I) and Anguilla anguilla agglutinin (AAA), each with a distinctive primary binding preference to type II and type I blood group H oligosaccharide determinants, respectively. In newly born and adult mice, direct labeling of isolated lymphocyte subsets in suspension, as well as immunohistochemical assays were indicative of the age-regulated co-expression of the UEA-I-reactive ligand among thymic epithelial cells and a subset of the mature (PNA −), medullary thymocytes. In the spleen, UEA-I-ligand expression was selectively confined to a subset of the CD4 + T lymphocytes scattered around red pulp sinuses in newly born mice, but distinctively localized within the T cell-dependent periarteriolar lymphoid sheath compartment in adult mice. Among thymocytes of adult mice, two-dimensional Western blots demonstrated the expression of the UEA-I-reactive ligand among multiple isoforms of three major 50, 114 and 180 kDa acidic glycoproteins, of which, heterogeneous weight and charge variants of the 114 kDa component were also evident among splenocytes. The expression of the AAA-reactive ligand was, on the other hand, restricted to a single major 120 kDa acidic glycoprotein, in addition to a minor molecular weight variant of 115 kDa, associated with a subset of immature IgM + B lymphocytes localized within the red pulp, in both newly born and adult mice. The significance of these findings is discussed in relation to mechanisms that govern lymphocyte maturation, selection and migration.