Effect of long-term prophylaxis in the development of cytomegalovirus-specific T-cell immunity in D+/R- solid organ transplant recipients.

BACKGROUND: This study aimed to characterize the dynamics of acquisition of cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) in CMV donor positive/recipient negative solid organ transplant (SOT) patients receiving long-term antiviral prophylaxis, and to determine whether development of CMI confers protection against CMV disease. METHODS: A prospective multicenter study was conducted in Spain from September 2009 to September 2012. Whole blood specimens were prospectively collected at 30, 90, 120, 200, and 365 days after SOT, and CMI was determined by enumeration of CMV pp65 and IE-1-specific CD69(+) /interferon-γ-producing CD8(+) and CD4(+) T cells by flow cytometry for intracellular cytokine staining. As part of a simultaneous clinical trial, patients received either early prophylaxis (in the first 3 days after transplantation) in the first period of the study or delayed prophylaxis (initiated at day 14) during the second period of the study. The impact of the dynamics of acquisition of CMV-specific CMI on the incidence of CMV disease was evaluated by Kaplan-Meier survival analysis. RESULTS: A total of 95 SOT recipients were recruited. CMV infection and disease occurred in 38 (40%) and 26 (27.4%) patients, respectively. The proportion of patients achieving any detectable CMV-specific CMI response at each of the different monitoring points was higher in liver transplant recipients, as compared to kidney or heart transplant recipients. The presence of any detectable response at day 120 or 200 was protective against the development of CMV disease (positive predictive values 92% and 93%, respectively). CONCLUSIONS: The rate of acquisition of CMV-specific CMI in SOT recipients undergoing antiviral prophylaxis differed significantly between different SOT populations. Patients developing any detectable CMI response were protected against the occurrence of CMV disease.

Effect of delaying prophylaxis against CMV in D+/R- solid organ transplant recipients in the development of CMV-specific cellular immunity and occurrence of late CMV disease.

OBJECTIVES: Evaluate the protective effect against late CMV disease of delaying antiviral prophylaxis initiation in D+/R- patients receiving solid organ transplant (SOT). METHODS: Prospective multicenter study in D+/R- SOT recipients in Spain (Sept/09-Sept/12). Whole blood specimens were prospectively collected after Tx for CMV-specific cell-mediated immunity (CMI) determination. Two prophylaxis strategies were compared: early prophylaxis (EP; starting within the first 3 days after Tx) and delayed prophylaxis (DP; starting 14 days after Tx). Risk factors for the occurrence of CMV disease were determined by survival analysis and proportional risk Cox regression models. RESULTS: We included 95 patients (50 EP V 45 DP). Twenty six patients (27.4%) developed CMV disease: 32.7% EP vs. 20% DP; (p = 0.2). No cases of CMV disease were reported previously to beginning delayed prophylaxis. The percentage of individuals with detectable CMI response was higher in patients with DP although differences did not reach statistic significance (42% vs 29.6% at day 200 after Tx; p = 0.4). There was a clear trend towards less end-organ CMV disease in patients receiving DP (18.2% EP vs 5% DP; p = 0.09) and DP was the only protective factor in the multivariate analysis (HR: 0.26; CI: 0.05-1.2; p = 0.09). CONCLUSIONS: A 14-day delay in CMV prophylaxis in D+/R- SOT recipients is safe and may reduce the incidence of late CMV end-organ disease although correlation of this effect with CMI responses was not complete.

Functional patterns of cytomegalovirus (CMV) pp65 and immediate early-1-specific CD8(+) T cells that are associated with protection from and control of CMV DNAemia after allogeneic stem cell transplantation.

BACKGROUND: The functional profile of cytomegalovirus (CMV)-specific CD8(+) T cells that associate with protection from and control of CMV DNAemia in allogeneic stem cell transplant (allo-SCT) recipients remains incompletely characterized. METHODS: We enumerated pp65 and immediate early (IE)-1-specific CD8(+) T cells expressing interferon-gamma, tumor necrosis factor-alpha, and CD107a, by flow cytometry in 94 patients at days +30 and +60 after allo-SCT. RESULTS: Fifty of 94 patients had CMV DNAemia within the first 100 days after transplant. CMV-specific CD8(+) T-cell responses (of any functional type) were more likely to be detected in patients who did not display CMV DNAemia than in those who did (P = 0.04). Qualitatively, no major differences in the functional signature of CMV-specific CD8(+) T cells were noted between patients who had or did not have CMV DNAemia. Patients displaying levels of polyfunctional CD8(+) T cells at day +30 >0.30 cell/µL had a lower risk of CMV DNAemia (positive predictive value 76%, and negative predictive value 43%). CONCLUSION: The presence of polyfunctional CD8(+) T cells (either expressing CD107a or not) was associated with lower levels of CMV replication, and higher frequency of self-resolved episodes. The data reported further clarify the role of polyfunctional CD8(+) T cells in control of CMV DNAemia in allo-SCT recipients.

Reconstitution of CMV pp65 and IE-1-specific IFN-γ CD8(+) and CD4(+) T-cell responses affording protection from CMV DNAemia following allogeneic hematopoietic SCT.

Threshold levels of CMV-specific T-cell populations presumably affording protection from active CMV infection in allo-SCT recipients have been proposed, but lack extensive validation. We quantified CMV pp65 and immediate-early 1-specific IFN-γ CD8(+) and CD4(+) T cell responses at days +30, +60 and +90 after transplantation in 133 patients, and established cutoff cell levels protecting from CMV DNAemia within the first 120 days after transplantation. No patients showing IFN-γ CD8(+) or IFN-γ CD4(+) T-cell counts >1.0 and >1.2 cells/µL, respectively, developed a subsequent episode of CMV DNAemia. Initial or recurrent episodes of CMV DNAemia occurred in the face of IFN-γ T-cell levels below defined thresholds. Negative predictive values at day +30 for the IFN-γ CD8(+) and CD4(+) T-cell markers were 68.1 and 61.8%, respectively. Recipients of grafts from CMV seropositive, related or HLA-matched donors, or receiving non-myeloablative conditioning had nonsignificant tendencies to reach more frequently protective levels of both T-cell subsets at early and late (day +365) times after transplantation. The use of anti-thymocyte globulin and umbilical cord blood transplantation were associated with impaired CMV-specific T-cell reconstitution. CMV-specific IFN-γ CD8(+) and CD4(+) T-cell recovery occurred irrespective of detectable CMV DNAemia.