Prevalence of polyreactive innate clones among graft-­infiltrating B cells in human cardiac allograft vasculopathy

https://doi.org/10.1016/j.healun.2017.09.011Get rights and content

Background

Cardiac allograft vasculopathy (CAV) has been associated with graft-infiltrating B cells, although their characteristics are still unclear. In this study we examined the frequency, localization and reactivity profile of graft-infiltrating B cells to determine their contribution to the pathophysiology of CAV.

Methods

B cells, plasma cells and macrophages were examined by immunohistochemistry in 56 allografts with CAV, 49 native failed hearts and 25 autopsy specimens. A total of 102 B-cell clones were immortalized directly from the infiltrates of 3 fresh cardiac samples with CAV. Their secreted antibodies were assessed using enzyme-linked immunoassay and flow cytometry.

Results

B-cell infiltration was observed around coronary arteries in 93% of allograft explants with CAV. Comparatively, intragraft B cells were less frequent and less dense in the intraventricular myocardium from where routine biopsies are obtained. Plasma cells and macrophages were also detected in 85% and 95% of explants, respectively. Remarkably, B-cell infiltrates were not associated with circulating donor-specific antibodies (DSA) or prior episodes of antibody-mediated rejection (AMR). Among all B-cell clones generated from 3 explants with CAV, a majority secreted natural antibodies reactive to multiple autoantigens and apoptotic cells, a characteristic of innate B cells.

Conclusions

Our study reveals a high frequency of infiltrating B cells around the coronary arteries of allografts with CAV, independent of DSA or AMR. These cells are enriched for innate B cells with a polyreactive profile. The findings shift the focus from conventional DSA-producing B cells to the potentially pathogenic polyreactive B cells in the development of clinical CAV.

Section snippets

Cardiac specimens

Tissue specimens from a total of 56 cardiac transplants were used in this study; 7 of these were fresh samples and the rest were tissue samples archived at the Columbia University Medical Center. The cardiac specimens were explanted during a second transplant procedure at Columbia University Medical Center, Massachusetts General Hospital (MGH) or Brigham and Women’s Hospital. The study was approved by all institutional review boards. The fresh tissues were obtained in the operating room and

Results

Tissues surrounding the CA as well as transmural epicardium to endomyocardium samples were obtained at 3 participating institutions from 56 cardiac allografts explanted at time of re-transplantation. These included 7 fresh cardiac allografts and 49 archived cardiac allograft specimens. Patients’ demographics are shown in Table 1. The presence of CAV was confirmed in all cases based on intimal thickening of intramural vessels. These specimens are henceforth referred to as CAV explants.

Discussion

B-cell infiltrates are frequent in cardiac allografts,13 yet their biologic significance is still uncertain. Herein, we have examined representative infiltrates in tissue specimens collected from 56 cardiac allograft explants with ongoing CAV. We primarily focused our investigations on the location of the B cells in the graft, their relation to previous episodes of AMR and circulating DSA, and, last, their reactivity profiles. Our studies revealed several unrecognized characteristics of

Disclosure statement

The authors have no conflicts of interest to disclose. This work was supported by grants from the Roche Organ Transplant Research Foundation (ROTRF), the National Institutes of Health (R01-AI116814, T32-HL-007854-21 to K.J.C., S10RR027050 for flow cytometry instrumentation) and Enduring Hearts (fellowship grant to S.B.S.).

References (30)

  • B. Gao et al.

    Pretransplant IgG reactivity to apoptotic cells correlates with late kidney allograft loss

    Am J Transplant

    (2014)
  • H. Cardinal et al.

    Antiperlecan antibodies are novel accelerators of immune-mediated vascular injury

    Am J Transplant

    (2013)
  • N. Singh et al.

    Circulating apoptotic endothelial cells and apoptotic endothelial microparticles independently predict the presence of cardiac allograft vasculopathy

    J Am Coll Cardiol

    (2012)
  • K.J. Clerkin et al.

    The effect of timing and graft dysfunction on survival and cardiac allograft vasculopathy in antibody-mediated rejection

    J Heart Lung Transplant

    (2016)
  • A. Loupy et al.

    Very late heart transplant rejection is associated with microvascular injury, complement deposition and progression to cardiac allograft vasculopathy

    Am J Transplant

    (2011)

    • Cited by (0)

    1

    Contributed equally to this work.

    View full text
    © 2017 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.