Germinal center marker GL7 probes activation-dependent repression of N-glycolylneuraminic acid, a sialic acid species involved in the negative modulation of B-cell activation.

ABSTRACT: Sialic acid (Sia) is a family of acidic nine-carbon sugars that occupies the nonreducing terminus of glycan chains. Diversity of Sia is achieved by variation in the linkage to the underlying sugar and modification of the Sia molecule. Here we identified Sia-dependent epitope specificity for GL7, a rat monoclonal antibody, to probe germinal centers upon T cell-dependent immunity. GL7 recognizes sialylated glycan(s), the alpha2,6-linked N-acetylneuraminic acid (Neu5Ac) on a lactosamine glycan chain(s), in both Sia modification- and Sia linkage-dependent manners. In mouse germinal center B cells, the expression of the GL7 epitope was upregulated due to the in situ repression of CMP-Neu5Ac hydroxylase (Cmah), the enzyme responsible for Sia modification of Neu5Ac to Neu5Gc. Such Cmah repression

SUBMITTER: Naito Y 

PROVIDER: S-EPMC1899932 | biostudies-literature | 2007 Apr

REPOSITORIES: biostudies-literature