intracellular IFNγ, IL-17 and IL-10 producing T cells correlates with the occurrence of post-transplant opportunistic infection in liver and kidney recipients.

Aim: To validate intracellular cytokine production functional assay as means of cell-mediated immunity monitoring of post-transplant patients with opportunistic infection (OI).

Methods: Intracellular cytokine-producing CD4 and CD8 T-cell monitoring was carried out in 30 liver transplant (LTr) and 31 kidney transplant (KTr) recipients from 2010 to 2012. Patients were assessed in our Department of Immunology at the Clinical University 'Hospital Virgen de la Arrixaca-IMIB' in Murcia, Spain for one year following transplantation. FACS Canto II flow cytometer was employed to quantify the intracellular production of IL-17, IFNγ and IL-10 cytokines on stimulated CD4CD69 and CD8CD69 T cells and BD FACS DIVA v.6 software was used to analysed the data. Statistical analysis was carried out using SPSS 22.0.

Results: LTr with OI had significantly lower % of CD8CD69IFNγ T cells at 60 (7.95 ± 0.77 26.25 ± 2.09, < 0.001), 90 (7.47 ± 1.05 30.34 ± 3.52, < 0.001) and 180 (15.31 ± 3.24 24.59 ± 3.28, = 0.01) d post-transplantation. Higher % of CD4CD69IL-10 as well as CD4CD69IL-17 T cells were yet reported at 30 (14.06 ± 1.65 6.09 ± 0.53, = 0.0007 and 4.23 ± 0.56 0.81 ± 0.14, = 0.005; respectively), 60 (11.46 ± 1.42 4.54 ± 0.91, = 0.001 and 4.21 ± 0.59 1.43 ± 0.42, = 0.03; respectively) and 90 d (16.85 ± 1.60 4.07 ± 0.63, < 0.001 and 3.97 ± 0.43 0.96 ± 0.17, = 0.001). Yet, KTr with OI had significantly lower percentage of CD4CD69IFNγ at 30 (11.80 ± 1.59 20.64 ± 3.26, = 0.035), 60 (11.19 ± 1.35 15.85 ± 1.58, = 0.02), 90 (11.37 ± 1.42 22.99 ± 4.12, = 0.028) and 180 (13.63 ± 2.21 21.93 ± 3.88, = 0.008) d post-transplantation as opposed to CD4CD69IL-10 and CD8CD69IL-10 T cells which percentages were higher at 30 (25.21 ± 2.74 8.54 ± 1.64, < 0.001 and 22.37 ± 1.35 17.18 ± 3.54, = 0.032; respectively), 90 (16.85 ± 1.60 4.07 ± 0.63, < 0.001 and 23.06 ± 2.89 10.19 ± 1.98, = 0.002) and 180 (21.81 ± 1.72 6.07 ± 0.98, < 0.001 and 19.68 ± 2.27 10.59 ± 3.17, = 0.016) d post-transplantation. The auROC curve model determined the most accurate cut-off values to stratify LTr and KTr at high risk of OI and Cox Regression model confirmed these biomarkers as the most significant risk factors to opportunistic infection.

Conclusion: Post-transplant percentages of T-cell subsets differed significantly amongst infected- and non-infected-LTr and -KTr and yet this imbalance was found to contribute towards a worst clinical outcome.