Endothelial L-Selectin Ligands Are Likely to Recruit Lymphocytes into Rejecting Human Heart Transplants

Abstract

L-selectin-dependent lymphocyte extravasation is a hallmark of acute heart allograft rejection in rats. On screening over 600 endomyocardial biopsies (EMBs), taken at different time points after heart transplantation in man , we identified 91 samples with histological signs of acute rejection. Rejection and nonrejection EMBs were analyzed for the presence of properly glycosylated , ie , sulfated sialyl Lewis-x (sLex) decorated L-selectin ligands. Two anti-sLex (2F3 and HECA-452) and one anti-6-or 6 -sulfated and/or 6 ,6 -bisulfation (MECA-79) monoclonal antibodies were used. Nonrejecting heart endothelium did not express, or expressed only weakly , sulfated and or sLex decorations of L-selectin ligands. On the contrary , these epitopes were readily detectable on endothelium of capillaries and venules at the onset and during acute rejection episodes. The more intense the sulfated sLex expression was , the more severe the rejection episode was in histological grading. The endothelial expression of L-selectin ligands decreased to background levels as the rejection resolved. Our data demonstrate a complete correlation between the level of expression of the sulfated sLex-decorated ligands on the one hand and the histological severity of acute heart allograft rejection on the other hand. These data suggest that functionally active endothelial L-selectin ligands are instrumental in lymphocyte extravasation into the human heart allografts at the onset and during acute rejection episodes. (Am J Pathol 1999, 155:1303-1310) Acute heart allograft rejection is characterized by heavy infiltration of lymphocytes. 1,2 To infiltrate the graft and to promote rejection, the lymphocytes extravasate from blood through the vascular endothelial layer into the graft parenchyma. 3-5 Extravasation of lymphocytes is initiated by an interaction of members of the selectin family and their oligosaccharide-containing ligands. L-selectin is expressed on leukocyte surfaces and recognizes its endothelial counterreceptors, such as GlyCAM-1, CD34, and MAdCAM-1, provided they are decorated with ␣2,3-sialylated, ␣1,3-fucosylated, and sulfated lactosamines. 6 -8 We and others have shown that high endothelial cells in lymph nodes express glycans fulfilling all or most of the above-listed requirements, the prototype decoration being sulfated sialyl Lewis x (sLex) for L-selectin. 9 -12 Importantly, endothelial cells under normal conditions in other locations do not express proper glycoforms of Lselectin ligands. However, proinflammatory stimuli in in vitro and animal studies have shown that endothelium can be induced to express these glycans de novo and to promote leukocyte extravasation. 2,13,14 Likewise, the endothelial E-and P-selectins have been shown to be inflammation-inducible molecules, both in animal models and in human patients. [15][16][17][18][19] A novel approach to increase immunosuppressive efficacy, without targeting activation and proliferation of T cells, would be to inhibit the carbohydrate-dependent entry of lymphocytes into the gr...

Induction of peripheral lymph node addressin in human gastric mucosa infected byHelicobacter pylori

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L-Selectin-Dependent Lymphoid Occupancy Is Required to Induce Alloantigen-Specific Tolerance

“…Nonetheless, previous studies show that anti-CD62L mAbs or CD62L deficiency are not generally immunosuppressive, but result in altered leukocyte distribution and kinetics of immune responses (20 -23). As shown in this study and previously (19,39), anti-CD62L mAbs do not prolong allograft survival, and CD62L Ϫ/Ϫ recipients are fully capable of vigorously rejecting allografts. Instead, interfering with CD62L function inhibits tolerization, and this is not due to costimulatory influences (Fig.…”

Human Solid Tumors Contain High Endothelial Venules: Association with T- and B-Lymphocyte Infiltration and Favorable Prognosis in Breast Cancer

“…Tumor HEVs are structurally and phenotypically similar to HEVs from patients suffering from autoimmune or chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel diseases, and autoimmune thyroiditis (15,18,19). The presence of HEVs in these pathologies has been shown to participate in the development and the maintenance of chronic inflammation through the recruitment of large numbers of lymphocytes (27,28). In contrast, HEVs have never been observed in normal nonlymphoid tissues.…”