Detection of a Sulfotransferase (HEC-GlcNAc6ST) in High Endothelial Venules of Lymph Nodes and in High Endothelial Venule-Like Vessels within Ectopic Lymphoid Aggregates

Abstract

The interaction of L-selectin on lymphocytes with sulfated ligands on high endothelial venules (HEVs) of lymph nodes results in lymphocyte rolling and is essential for lymphocyte homing. The MECA-79 monoclonal antibody reports HEV-expressed ligands for L-selectin by recognizing a critical sulfation-dependent determinant on these ligands. HEC-GlcNAc6ST, a HEV-localized sulfotransferase, is essential for the elaboration of functional ligands within lymph nodes, as well as the generation of the MECA-79 epitope. Here, we use an antibody against murine HEC-GlcNAc6ST to study its expression in relationship to the MECA-79 epitope. In lymph nodes, the enzyme is expressed in the Golgi apparatus of high endothelial cells, in close correspondence with luminal staining by MECA-79. In lymph node HEVs of HEC-GlcNAc6ST-null mice, luminal staining by MECA-79 is almost abolished, whereas abluminal staining persists although reduced in intensity. HEV-like vessels in several examples of inflammation-associated lymphoid neogenesis, including nonobese diabetic mice, also exhibit concomitant expression of the sulfotransferase and luminal MECA-79 reactivity. The correlation extends to ectopic lymphoid aggregates within the pancreas of RIP-BLC mice, in which CXCL13 is expressed in islets. Analysis of the progeny of RIP-BLC by HEC-GlcNAc6ST-null mice establishes that the enzyme is responsible for the MECA-79 defined luminal ligands.

N-Acetylglucosamine 6-O-Sulfotransferase-1 Regulates Expression of L-Selectin Ligands and Lymphocyte Homing

“…In view of the results on GlcNAc6ST-2 null mice (30, 31), we conclude that both GlcNAc6ST-1 and GlcNAc6ST-2 contribute to the synthesis of the abluminal MECA-79 epitope in PLN and MLN, and it is most likely that only GlcNAc6ST-1 is involved in formation of the abluminal epitope in PP (Table II). This latter finding is consistent with the absence of GlcNAc6ST-2 protein in PP HEV (35). The function of the abluminal L-selectin ligand is not presently known.…”

“…To distinguish the MECA-79 epitope in the abluminal aspects of HEV from the epitope in the luminal aspects, a two-step in vivo/ex vivo staining approach was employed (35). Unlabeled MECA-79 (50 g/ mouse in 100 l of PBS) was infused into the tail veins of mice and allowed to circulate for 30 min.…”

“…Furthermore, the mice could be utilized to investigate mechanisms of inflammation-associated lymphoid neogenesis in which MECA-79-positive vessels are prominent (35,48).…”

Transgenic LacZ under control of Hec-6st regulatory sequences recapitulates endogenous gene expression on high endothelial venules

“…Ectopic accumulations of lymphoid cells that have characteristics of organized lymphoid tissue are found in many types of chronic inflammatory stimulation, including autoimmune diseases, such as type I diabetes and rheumatoid arthritis, graft rejection, and microbial infection (8,(11)(12)(13). These accumulations, termed tertiary lymphoid organs or tissues (TLO), arise through a process called lymphoid neogenesis (14).…”

“…These accumulations, termed tertiary lymphoid organs or tissues (TLO), arise through a process called lymphoid neogenesis (14). HEV found in such TLO frequently express PNAd and HEC-6ST (11,12). Although it is not clear whether the expression of PNAd in these pathological situations is a prerequisite or the consequence of the chronic inflammatory process, the presence of HEV allows entrance of naïve cells into the site and provides the possibility of further damage through the process of epitope spreading (15).…”