The Frequency of Tissue-Resident Donor T and NK Cells in Peripheral Blood after Lung Transplantation is Modulated by Normothermic Ex Vivo Lung

The Frequency of Tissue-Resident Donor T and NK Cells in Peripheral Blood after Lung Transplantation is Modulated by Normothermic Ex Vivo Lung

S158 The Journal of Heart and Lung Transplantation, Vol 38, No 4S, April 2019 TCRb chain gene rearrangements were used to link single-cell and TCR r...

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S158

The Journal of Heart and Lung Transplantation, Vol 38, No 4S, April 2019

TCRb chain gene rearrangements were used to link single-cell and TCR repertoires. Results: Overlap between intragraft and blood T cell repertoires was observed in all 4 cases with most high frequency rearrangements present in both compartments (Fig. 1a). The clonality index was higher in the blood compared to the graft. In contrast, there was minimal overlap in the B cell repertoire from the same samples (example in 1b). Strikingly, in each case, a common high frequency TCRb in the blood was also amongst the top rearrangements in the CA, endo, and a previous biopsy (Quilty lesion or cellular rejection) obtained 2 to 6 years earlier (1c). Using their unique TCRb sequence as a link to the single-cell phenotype data, we identified these clones as CD8+CD45RA+Tbet+ T-cells evocative of effector memory RA T cells (Temra). Conclusion: Our studies demonstrated considerable overlap between the graft and blood TCR repertoire in CAV suggestive of a bystander T cell response in situ. However, these findings do not rule out the existence of individual clones being expanded in the graft. Moreover, the Temra phenotype of persistent high frequency clones offers a first indication of the type of T cells infiltrating cardiac allografts.

Results: In all lung recipients, the NK cell frequency was significantly increased at T0 and T24 (p=0.04), CD4 T cells decreased and CD8 T cells remained stable. No significant differences were seen between recipients of standard vs OCS preserved lungs. Donor NK cells comprised 18.8% at T0, 17.1% at T24 and 7.8% at 3 wk (p<0.001) of circulating NK cells. Frequencies were for donor CD8+ T cells 8.3%, 6.6% and 2.6%, and for CD4 + donor T cells 6.4%, 4.6% and 1.3% of the respective subset. At T0, significantly less donor NK cells were detected in recipients of OCS lungs (p<0.008), while T cells were reduced non-significantly. No correlation between donor NK or T cell frequencies was observed for CIT or PGD. In the limited number of patients at risk, a trend towards higher early donor T cell frequencies in recipients not developing CLAD at two years after Tx was observed (p=0.04). Conclusion: Donor T and NK cells are detectable in blood of all lung recipients during the first 3 weeks after Tx and did not correlate with CIT or PGD. Preservation with portable EVLP resulted in decreased NK cell frequencies which might be explained by their ex vivo mobilization. Furthermore, transient donor chimerism might have a protective effect against CLAD development. 368 Persisting Donor Alveolar Macrophages Have Increased Expression of Scavenger Receptor CD206 Compared to Graft-Infiltrating RecipientDerived Macrophages Following Lung Transplantation M.E. Snyder,1 S.P. Weisberg,2 T. Connors,3 L. Benvenuto,4 L. Shah,4 H.J. Robbins,4 J.L. Hook,4 F. D'Ovidio,5 J. Sonett,5 S. Arcasoy,4 and D.L. Farber.5 1Medicine, University of Pittsburgh, Pittsburgh, PA; 2Pathology, Columbia University, New York, NY; 3Pediatrics, Columbia University, New York, NY; 4Medicine, Columbia University, New York, NY; and the 5 Surgery, Columbia University, New York, NY.

367 The Frequency of Tissue-Resident Donor T and NK Cells in Peripheral Blood after Lung Transplantation is Modulated by Normothermic Ex Vivo Lung C. Falk,1 B. Wiegmann,2 A. Hitz,1 R. Bellmas-Sanz,1 K. Bl€asing,1 F. Ius,2 C. K€ uhn,2 M. Avsar,2 I. Tudorache,2 A. Haverich,2 and G. Warnecke.2 1Institute of Transplant Immunology, Hannover Medical School, Hannover, Germany; and the 2Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany. Purpose: The appearance of passenger donor lymphocytes in recipient blood after double lung transplantation has been described decades ago. However, neither their early kinetics, nor distribution of lymphocyte subsets and clinical relevance have been addressed in detail. Therefore, we investigated frequencies and phenotypes of donor T and NK cells within the first 24 hours and at 3 weeks after lung transplantation and correlated them to important clinical outcomes. Methods: Blood and perfusion solutions of 59 lung recipients (30 male, 29 female, median age 51) were analysed pre Tx, at T0, T24 and at three weeks (3wk) for NK and T cell subsets. In a subset of 20 patients with standard cold donor lung preservation and 9 preserved with portable ex vivo lung preservation (OCS Lung), donor T and NK cells were identified in blood by staining of donor HLA alleles (HLA-A1,A2,A11,A24) combined with lineage markers. Frequencies of donor lymphocytes were correlated to cold ischemic time (CIT), primary graft dysfunction (PGD) and chronic lung allograft dysfunction (CLAD).

Purpose: Alveolar macrophages play vital roles in attenuating lung injury through immune modulatory effects and improving gas exchange by scavenging cellular debris within the alveoli. A recent analysis of lung biopsy specimens suggests that donor-derived macrophages persist within the allograft after lung transplantation. The phenotypic differences between donor and graft-infiltrating recipient macrophages remains unreported. Methods: Single cell suspensions obtained from bronchoalveolar lavage (BAL) of 15 lung transplant recipients at various times following transplantation were analyzed by flow cytometry. Macrophages were defined as CD45+CD3-CD19-CD64+CD14+CD11chisinglets. Cell origin (donor versus recipient) was identified by staining for human leukocyte antigen discrepancies. Paired t test was used to compare cell surface marker expression between donor and recipient macrophages. Results: The proportion of donor macrophages within the BAL was variable across patients but did not vary over the time following transplantation (p = 0.5). The median percentage of donor macrophages was 10.5% (range 1-64). Donor macrophages had increased expression of CD206 (Figure: Rep. flow cytometry plot from BAL one month following transplantation and cumulative data from 10 participants, p = 0.004), with trends in increased expression of HLADR (p = 0.07), and no difference in CD163 expression (p = 0.17). Conclusion: The scavenger function of alveolar macrophages is vital in maintaining gas exchange in the setting of severe influenza infection. Following lung transplantation, persisting donor-derived alveolar macrophages have significantly increased expression of the scavenger receptor CD206 when compared to graft-infiltrating recipient-derived macrophages. Further investigation is warranted to identify whether this has implications for graft function in the perioperative setting.