Human cytomegalovirus (HCMV) is a common opportunistic pathogen in transplant recipients. Patterns of viremia and reactivation are influenced by the host immune response, including CD8+ T cells. However, the cellular deficits or phenotypic differences that account for differential outcomes during HCMV viremia are incompletely understood.
Peripheral blood mononuclear cells were collected from 20 transplant recipients (10 viremia controllers and 10 noncontrollers) at onset of HCMV viremia and 4 weeks postonset. We used mass cytometry to perform in-depth characterization of cell surface and intracellular CD8+ T cell markers and to compare frequencies of these cells between groups.
Deep profiling identified 2 central memory T cell subsets at onset and 5 terminally differentiated memory T (TEMRA) cell subsets at 4 weeks that were associated with control of HCMV viremia, in addition to 6 TEMRA subsets at onset and 4 weeks associated with relapsing or remitting HCMV viremia. In general, CD8+ T-cell clusters associated with poorly controlled HCMV viremia lacked markers of activation or terminal differentiation including CD38, CD69, CD25, CD57, and HLA-DR. We also measured the production of 8 HCMV-specific effector molecules (TNFα, IFNγ, interleukin 2, granzyme B, perforin, macrophage inflammatory protein 1β, interleukin 10, and CD107a) in CD8+ T cells. Viremia controllers had greater diversity of HCMV-specific multifunctional responses at both time points, including significantly higher frequencies of HCMV-specific TNFα+IFNγ+ CD8+ T cells at onset. These multifunctional cells had a phenotype consistent with activated TEM/TEMRA cells.
Uncontrolled CMV viremia is associated with specific clusters of memory T-cell subsets and lower frequencies of HCMV-specific multifunctional CD8+ T cells.
1Transplant Infectious Diseases and Multi-Organ Transplant Program, University Health Network, Toronto, Canada.
Received 26 March 2018. Revision received 24 June 2018.
Accepted 11 July 2018.
This study was funded by the Canadian National Transplant Research Program (CNTRP).
A.H. has received a research grant from Roche and Qiagen, consulting fees from Astellas and Chimerix. D.K. has received research grants from Roche, Qiagen and Oxford Immunotec and consulting fees from Qiagen and Oxford Immunotec.
V.H.F. participated in performance of the research, data analysis, and writing of the paper. D.K. participated in research design, data interpretation, data collection, and writing of the article. A.H. participated in research design, data interpretation, data collection, and writing of the article.
D.K. and A.H. have Indicates joint senior authorship.
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Correspondence: Atul Humar, MD, MSc, FRCPC, PMB 11-175, 585 University Ave, Toronto, Canada M5G 2N2. (email@example.com).