Distinct binding patterns of fucose-specific lectins from Biomphalaria alexandrina and Lotus tetragonolobus to murine lymphocyte subsets

The putative expression of distinct terminally fucosylated glycoconjugates among murine lymphocyte subpopulations was sought using a Biomphalaria alexandrina-derived lectin (BaSI), of proven specificity to a fucosyllactose determinant, and the fucose-binding lectin from Lotus tetragonolobus seeds. Direct labeling of isolated lymphocyte subsets in suspension as well as immuno-histochemical and two-dimensional Western blotting assays demonstrated the exclusive expression of the BaSI-reactive ligand among multiple isoforms of two major 95 and 92 kDa and a minor 82 kDa acidic glycoproteins, selectively localized to the splenic marginal zone B lymphocytes of adult mice. The expression of the L. tetragonolobus lectin-reactive ligand was, on the other hand, restricted primarily to a single homogeneous 50 kDa acidic glycoprotein associated with a subset of the mature (PNA−) medullary thymocytes of adult mice as well as a minority of the immature (PNA+) thymocytes within the deep cortical region in newly born mice. The significance of these findings is discussed in relation to mechanisms that govern lymphocyte development and homing.