BACKGROUND: Control of cytomegalovirus (CMV) infection after solid organ transplantation (SOT) requires a functional immune system. We assessed the association between quantitation and function of CMV-specific CD8+ T cells and CMV infection in SOT recipients. METHODS: During a 10-year period, selected kidney, heart, lung, pancreas, liver, and composite tissue recipients were tested for CMV-specific CD8+ T cells immune competence (CMV-CD8+), as measured by enumeration, interferon-gamma production, and CD107a/b degranulation. Quantitative and functional data were used to assemble T-cell immune competence (TIC) score. CMV infection was diagnosed by polymerase chain reaction in blood and other samples or histopathology. RESULTS: Of 130 patients tested, 59 had CMV infection or disease. The median onset to CMV infection was 10.5 months (interquartile range [IQR], 5.5-18.7). Gastrointestinal disease (28.8%), pneumonia (20.3%), and CMV syndrome (17%) were most common presentation. An impaired nonspecific or CMV-CD8+ TIC score was associated with tissue-invasive disease (hazard risk, 2.84, 95% confidence interval, 1.03-11.81; P = 0.04). Patients with impaired CMV-CD8+ TIC score had longer viremia duration (42.4 days vs 18.8 d; P < 0.001). Patients with impaired nonspecific or CMV-CD8+ TIC score had higher risk of relapse (68.8% vs 27.9%; hazard risk, 2.56; 95% confidence interval, 1.09-5.89; P = 0.03). Patients with CMV infection or disease had lower median absolute lymphocyte count (380 [IQR, 240-540] vs 940 [IQR, 551-1210] cells/mm; P < 0.0001) and CD4+ T cell count (29 cells/mm [IQR, 1.3-116.0] vs 325.5 cells/mm [IQR, 151.5-589.8]; P < 0.0001). CONCLUSIONS: Nonspecific and CMV-specific CD8+ T-cell function correlated with the course of CMV after SOT, and measuring these has the potential to assist in its clinical management.
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