Natural Killer Cell Antibody Receptor Engagement In Antibody-Mediated Allograft Rejection

• Author / Creator

  Parkes, Michael D

• Background: NK cells are a key cellular component of antibody-mediated rejection (ABMR), but their role in ABMR has not been identified. We postulated that NK cells are stimulated through their CD16a antibody receptors by donor-specific anti-HLA antibodies in ABMR. There is currently no direct evidence supporting this phenomenon, although it is often assumed to occur. Given some of the similarities between NK cells and CD8 effector T cells that drive T cell-mediated rejection (TCMR), we further hypothesized that some CD16a-inducible NK cell transcripts are also induced by T cell receptor (TCR) stimulation of CD8 T cells in TCMR. Methods: We characterized transcripts that were CD16-inducible in NK primary human NK cells in vitro, and studied their expression in human kidney transplant biopsies with ABMR. We used an extended human cell panel to determine these transcripts’ selectivity for NK cells. We also examined these transcripts’ expression in primary human CD8 T cells stimulated in vitro through CD3/TCR. In vitro soluble mediator production by CD16a-stimulated NK cells and CD3/TCR-stimulated CD8 T cells was assessed using a multiplex platform. Results: 276 transcripts were increased in CD16a-stimulated versus unstimulated NK cells (FC>2x, FDR<0.05), including IFNG, TNF, CSF2, multiple proinflammatory chemokines (e.g. CCL3, CCL4, XCL1) and modulators of NK cell effector functions (e.g. TNFRSF9, CRTAM, CD160). Many CD16a-inducible ii transcripts were also CD3/TCR-inducible in CD8 T cells. Multiplex analysis of 30 different soluble mediators in stimulated NK cell and CD8 T cell culture supernatants revealed that both produced CCL3, CCL4, IFNG, TNF, and CSF2, but not the other 25 mediators. Eight of the top 30 CD16a inducible transcripts were strongly associated with ABMR, including NK-selective transcripts CD160 and XCL1. Many NK cell transcripts such as GNLY and SH2D1B were increased in ABMR but were not CD16a-inducible, probably reflecting NK cell localization. 12 of the top 30 CD16a-inducible transcripts were highly associated with TCMR, and six of these were strongly associated with ABMR as well. Conclusions: The association of NK cell-selective transcripts with ABMR provides direct evidence of CD16a-mediated NK cell activation in ABMR. The overlap in CD3/TCR-inducible and CD16a-inducible transcripts and soluble mediators illustrates shared effector potential between NK cells and CD8 T cells. Top CD16a-inducible ABMR-associated NK cell transcripts are also associated with TCMR because they are strongly inducible in CD8 T cells following CD3/TCR stimulation.

• Subjects / Keywords

  • Transplant
  • Antibody
  • T cell
  • Immunology
  • Nk cells
  • Rejection

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3KS6JF8N

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.