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Abstract: FR-PO272

The Conundrum of Normal Kidney Endothelial HLA-DR Clarified by Checkpoint Inhibitor Toxicity: A Role for Microvascular Endothelium in Peripheral Tolerance

Session Information

Category: Onconephrology

  • 1700 Onconephrology


  • Muczynski, Kimberly A., University of Washington, Seattle, Washington, United States

Years ago we reported high constitutive expression of HLA-DR on microvascular endothelial cells of normal human kidney in the absence of inflammation. This surprised us and seemed incongruent with what is known about HLA class II antigen processing. Peptides bound to class II molecules are derived from the uptake of extracellular proteins which get processed intracellularly and then exported to the cell surface bound to HLA-DR where they can be recognized by specific T cell receptors. Would it, therefore, not be dangerous to have kidney endothelial cells constitutively express HLA-DR on their surface where they might encounter and activate circulating T cells?


We used flow cytometry and and T cell activity assays to investigate the role of HLA-DR on human kidney microvascular endothelial cells (KMEC).


First, we show T cell proliferation and gamma interferon secretion of sensitized T cell when influenza hemagglutinin peptide is presented by KMEC of the appropriate HLA-DR specificity. Blockade of CD58 or HLA-DR reduces T cell activation while blockade of CD274 (PD-L1) enhances activation. Second, T cell co-stimulatory and inhibitory molecules on normal native and transplanted kidneys are identified by flow cytometry. CD274 expression is high on all KMECs and T cells within the kidney express CD279 (PD-1). Third, biopsies of acute kidney injury associated with checkpoint inhibitors that block the PD-1, PDL-1 axis show an intense perivascular lymphocytic infiltrate. Finally, human fetal kidneys express endothelial HLA-DR and CD274 at a similar time in development suggesting a fundamental property of the endothelial cells rather than resulting from an immune response.


Taken together, we propose a mechanism of peripheral tolerance whereby KMEC HLA-DR limits activation of sensitized T cells, even if a bound peptide is recognized, because of the constitutive high-co-expression of CD274 (PDL-1).


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