Poster Presentation The Australasian Society for Immunology 2017 Annual Scientific Meeting

Modulation of leucocyte populations as a result of coronary artery bypass grafting (#199)

Alexis J Perros 1 2 3 , Kelly Rooks 1 , Fenny Chong 1 , Arlanna Esguerra-Lallen 1 2 3 , Sanne Engkilde-Pedersen 1 2 3 , Rishendran Naidoo 4 , John-Paul Tung 1 2 3 5 , John F Fraser 2 3 4 , Peter Tesar 4 , Marc Ziegenfuss 6 , Susan Smith 4 , Donalee Obrien 4 , Robert L Flower 1 5 , Melinda M Dean 1 3 5
  1. Research and Development, Australian Red Cross Blood Service, Brisbane, QLD, Australia
  2. School of Medicine, University of Queensland, Brisbane, QLD, Australia
  3. Critical Care Research Group (CCRG), The Prince Charles Hospital, Brisbane, QLD, Australia
  4. Cardiothoracic Services, The Prince Charles Hospital, Brisbane, QLD, Australia
  5. Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia
  6. Adult Intensive Care Services, The Prince Charles Hospital, Brisbane, QLD, Australia

Introduction

Coronary artery bypass grafting (CABG) is a complex procedure that triggers a systemic inflammatory response that may contribute to adverse patient outcomes. Exposing patient blood to extracorporeal circuitry associated with bypass has been reported to initiate a complex reaction of inflammatory cytokine release and modulation of leucocyte subsets which may contribute to development of adverse outcomes. This study aimed to address the limited understanding of the impact of bypass and cardiac surgery on immunoregulatory leucocyte populations in circulation.

 

Methods

Blood was collected from CABG patients (n=33) at 5 time-points (Admission, Peri-operative, ICU, Day3 (D3), D5). The absolute count (Trucount, BD Biosciences) of B-cells (CD20+), NK-cells (CD56+), monocytes (CD14+), T-cell subsets (CD3+; helper CD4+; cytotoxic CD8+, regulatory CD25+CD127+) and dendritic cell (DC) subsets (myeloid [mDC] Lin-HLA-DR+CD11c+ and plasmacytoid [pDC] Lin-HLA-DR+CD11c-CD123+) was determined. Changes in the absolute cell counts were compared using repeated-measures one-way ANOVA with Dunnett’s post-test (admission sample as comparator, P<0.05)

 

Results

CABG resulted in significant modulation of multiple cell populations with cell-subset specific changes evident. Monocytes were elevated from the ICU period and B-cells elevated by D3 post-surgery. In contrast, CABG was associated with a significant decrease in both cytotoxic and helper T-cell numbers which was evident from the ICU period. While helper T-cell numbers recovered by D5 post-surgery, cytotoxic T-cells remained reduced. mDCs were decreased during CABG while pDC were elevated during surgery before decreasing during the ICU period.

 

Conclusion

Our data demonstrate significant differential perturbation of leucocyte subsets following CABG surgery. We found that the numbers of most cells returned to admission levels by D5 with the exception of cytotoxic T-cells which remained reduced which may increase the risk of infection. We are currently investigating whether subset-specific changes are associated with patient outcomes and may serve as predictive biomarkers for adverse patient outcomes.