Assessment of the potential value of plasma Torque Teno virus DNA load monitoring to predict cytomegalovirus DNAemia in patients with hematological malignancies treated with small molecule inhibitors: A proof-of-concept study.

It is unknown whether Torque Teno virus (TTV) DNA load monitoring could anticipate the development of infectious events in hematological patients undergoing treatment with small molecular targeting agents. We characterized the kinetics of plasma TTV DNA in patients treated with ibrutinib or ruxolitinib and assessed whether TTV DNA load monitoring could predict the occurrence of Cytomegalovirus (CMV) DNAemia or the magnitude of CMV-specific T-cell responses. Multicenter, retrospective, observational study, recruiting 20 patients treated with ibrutinib and 21 with ruxolitinib. Plasma TTV and CMV DNA loads were quantified by real-time PCR at baseline and days +15, +30, +45, +60, +75, +90, +120, +150, and +180 after treatment inception. Enumeration of CMV-specific interferon-γ (IFN-γ)-producing CD8+ and CD4+ T-cells in whole blood was performed by flow cytometry. Median TTV DNA load in ibrutinib-treated patients increased significantly (p = 0.025) from baseline (median: 5.76 log10 copies/mL) to day +120 (median: 7.83 log10 copies/mL). A moderate inverse correlation (Rho = -0.46; p < 0.001) was found between TTV DNA load and absolute lymphocyte count. In ruxolitinib-treated patients, TTV DNA load quantified at baseline was not significantly different from that measured after treatment inception (p ≥ 0.12). TTV DNA load was not predictive of the subsequent occurrence of CMV DNAemia in either patient group. No correlation was observed between TTV DNA loads and CMV-specific IFN-γ-producing CD8+ and CD4+ T-cell counts in either patient group. The data did not support the hypothesis that TTV DNA load monitoring in hematological patients treated with ibrutinib or ruxolitinib could be useful to predict either the occurrence of CMV DNAemia or the level of CMV-specific T-cell reconstitution; nevertheless, due to the small sample size, further studies involving larger cohorts are warranted to elucidate this issue.

Features of cytomegalovirus DNAemia and virus-specific T-cell responses in allogeneic hematopoietic stem-cell transplant recipients during prophylaxis with letermovir.

BACKGROUND: There is scarce information on the natural kinetics of cytomegalovirus (CMV) DNAemia and dynamics of CMV-specific T-cell reconstitution in allogeneic hematopoietic transplant recipients (allo-HSCT) undergoing letermovir (LMV) prophylaxis. METHODS: Twelve adult CMV-seropositive high-risk recipients (median age, 53 years; 9 males/3 females) undergoing LMV prophylaxis and 13 non-LMV allo-HSCT controls (median age, 58 years; 7 males/6 females) were included. CMV DNAemia in plasma was monitored by real-time polymerase chain reaction. Preemptive antiviral therapy (PET) was administered upon detection of ≥1500 IU/ml. CMV-specific interferon-gamma (IFN-γ)-producing CD8+ and CD4+ T cells were enumerated by flow cytometry around days +30, +60, and +90 after allo-HSCT. Ex vivo experiments assessing of the potential effect of LMV on CMV-specific T-cell expansion in a single CMV-seropositive donor were also conducted. RESULTS: Five LMV patients (41.6%) developed CMV DNAemia that cleared spontaneously. Four patients (33.3%) developed CMV DNAemia after LMV cessation, of which two required PET. Nine non-LMV patients (69.2%) developed CMV DNAemia (five required PET). The percentage of LMV and non-LMV patients exhibiting detectable CMV-specific T-cell responses was comparable (7/10 vs. 10/13; p = .71). Nevertheless, median CMV-specific CD4+ and CD8+ T-cell counts were lower in LMV patients by days +60 (p = .006 and .02, respectively) and +90 (p = .08 and .02). Ex vivo, CMV-specific CD8+ T cells expanded to the same level either in the presence (19.8%) or in the absence of LMV (20.6%). CONCLUSIONS: In our series, episodes of CMV DNAemia in LMV patients cleared spontaneously. A diminished degree of CMV-specific T-cell reconstitution in LMV patients compared to non-LMV patients was observed.

Impact of cytomegalovirus immunodominant HLA-I donor-recipient matching on the incidence and features of virus DNAemia and virus-specific T-cell immune reconstitution in unmanipulated haploidentical hematopoietic stem cell transplantation.

BACKGROUND: We investigated whether donor-recipient mismatch involving one or more cytomegalovirus (CMV) immunodominant (ID) human leukocyte antigen (HLA)-I alleles may impact on the degree of CMV pp65/immediate-early 1 (IE-1) T-cell reconstitution and the incidence of CMV DNAemia in patients undergoing unmanipulated haploidentical hematopoietic stem cell transplantation with high-dose posttransplant cyclophosphamide (PT/Cy-haplo). METHODS: Multicenter observational study including 106 consecutive adult PT/Cy-haplo patients (34 CMV ID HLA-I matched and 72 mismatched). A real-time PCR was used for plasma CMV DNA load monitoring. Enumeration of CMV-specific (pp65/IE-1) interferon (IFN)-γ-producing T cells from several patients was performed by flow cytometry by days +30, +60, +90 and +180 after transplantation. RESULTS: The cumulative incidence of CMV DNAemia, clinically significant CMV DNAemia episodes (cs-CMVi), and recurrent CMV DNAemia was comparable across CMV ID HLA-I matched and mismatched patients (71.8% vs. 80.9%, p = .95; 40.7% vs. 44.2%, p = .85; 16.4% vs. 28.1%; p = .43, respectively). The percentage of patients exhibiting detectable CMV-specific IFN-γ-producing T-cell responses (either CD8+ or CD4+ ) was similar across groups; nevertheless, significantly higher CMV-specific CD8+ T-cell counts were enumerated in the CMV ID HLA-I matched compared to mismatched patients by day +60 (p = .04) and +180 (p = .016) after transplantation. CONCLUSION: CMV ID HLA-I matching may impact on the magnitude of CMV-pp65/IE-1-specific CD8+ T-cell reconstitution; yet, this effect seemed not to have an impact on the incidence of initial, recurrent CMV DNAemia, or cs-CMVi.

Biomarker profile predicts clinical efficacy of extracorporeal photopheresis in steroid-resistant acute and chronic graft-vs-host disease after allogenic hematopoietic stem cell transplant.

We conducted a multicenter interventional study to assess the efficacy of Therakos ECP to treat steroid-resistant graft-vs-host disease (SRes-GVHD) after allogeneic HSCT and to identify biomarkers of GVHD response. A total of 62 patients were treated for acute SRes-GVHD (n = 37) or chronic SRes-GVHD (n = 25). Median time to best response was 35 days (range, 28-85) and 90 days (range, 27-240) in acute and chronic SRes-GVHD, respectively. Overall, 27 patients (72.9%) with SRes-aGVHD responded to treatment (40.5% CR and 32.4% PR). The response rate was significantly higher in grade I-II than in grade III-IV aGVHD (100% vs 50.0%, respectively, P-value = .001). In chronic SRes-GVHD, 22 patients (88%) achieved a clinical response (24.0% CR and 64% PR). Response was higher in moderate than in severe SRes-cGVHD (100% vs 75%, P = .096). In both acute and chronic SRes-GVHD patients, the percentage of peripheral blood CD3+ CD4+ was higher and CD3+ CD8+ lower in responding than nonresponding patients. Acute SRes-GVHD responding patients presented a higher number of Treg cells (CD4+ CD25+ CD127low/- ) at day 0 (P = .028) than nonresponding patients, differences that were maintained over the observation period. Phenotypic analysis of T-cell maturation showed a trend toward reduction in TCD8 naive cells, along with an increased percentage of TCD8 Mem Efect T cells after starting ECP in responding patients. None of the studied serum cytokines displayed statistically significant changes in either acute or chronic SRes-GVHD. ECP is an effective treatment for patients with SRes-GVHD. Biomarkers could help guide decision-making on ECP treatment initiation and duration.

Impact of clinical features, cytogenetics, genetic mutations, and methylation dynamics of CDKN2B and DLC-1 promoters on treatment response to azacitidine.

Azacitidine (AZA) is a DNA hypomethylation agent administered in myeloid neoplasms; however, there is still a lack of established predictors of response. We studied 113 patients with myelodysplastic syndromes (n = 85) or acute myeloid leukemia (n = 28) who received AZA to assess the predictive value on response of clinical features, cytogenetics, and molecular markers. Overall, 46 patients (41%) responded to AZA. Platelet doubling after the first AZA cycle was associated with a better response (68% vs. 32% responders, P = 0.041). Co-occurrence of chromosome 7 abnormalities and 17p deletion was associated with a worse response (P = 0.039). Pre-treatment genetic mutations were detected in 98 patients (87%) and methylation of CDKN2B and DLC-1 promoters were detected in 50 (44%) and 37 patients (33%), respectively. Patients with SF3B1 mutations showed a better response to AZA (68% vs. 35% responders, P = 0.008). In contrast, subjects with mutations in transcription factors (RUNX1, SETBP1, NPM1) showed a worse response (20% vs. 47% responders, P = 0.014). DLC-1 methylation pre-treatment was associated with poor clinical features and its reduction post-treatment resulted in a better response to AZA in MDS patients (P = 0.037). In conclusion, we have identified several predictors of response to AZA that could help select the best candidates for this treatment.

Kinetics of inflammatory biomarkers in plasma predict the occurrence and features of cytomegalovirus DNAemia episodes in allogeneic hematopoietic stem cell transplant recipients.

Cytomegalovirus (CMV) DNAemia occurs frequently in CMV-seropositive allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients, and usually results from reactivation of latent infection established in the recipient. Predicting the occurrence of CMV DNAemia may be helpful in managing CMV infection in allo-HSCT recipients. Here, the kinetics of several inflammatory biomarkers in plasma were characterized and assessed for their potential value in anticipating the development and features of active CMV infection in allo-HSCT recipients, as documented using real-time PCR assays. The cohort consisted of 46 non-consecutive adult patients who underwent T-cell replete allo-HSCT at our center. Plasma levels of C-reactive protein (CRP), soluble tumor necrosis factor receptor type 2 (sTNF-R2), transforming growth factor-ß1 (TGF-ß1), and interferon-inducible protein 10 (IP-10/CXCL10) were measured in consecutive specimens obtained from conditioning either by nephelometry (CRP) or by specific immunoassays (the rest). Of the 46 patients, 22 had a first episode of CMV DNAemia at a median of 34 days after allo-HSCT (range, day 19-day 50). We found that both the TGF-ß1 area under a curve (AUC) and peak levels were significantly lower in patients who subsequently developed CMV DNAemia than in patients with no CMV DNAemia. Interestingly, CRP but not TGF-ß1 AUC and peak levels predicted the occurrence of CMV DNAemia episodes requiring preemptive antiviral therapy. The data presented herein suggest that kinetics of inflammatory biomarkers in plasma might be useful to anticipate post-engraftment CMV DNAemia episodes and predict the need for preemptive antiviral therapy in allo-HSCT recipients.

Therapy-related acute myeloid leukemia developing 14 years after allogeneic hematopoietic stem cell transplantation, from a persistent R882H-DNMT3A mutated clone of patient origin.

BACKGROUND: Therapy-related acute myeloid leukemia (t-AML) develops in patients with prior exposure to cytotoxic therapies. Selection of a pre-existing TP53 mutated clone prone to acquire additional mutational events has been suggested as the main pathogenic mechanism of t-AML. Here, we report a unique case of t-AML which developed from a pre-existing DNMT3A mutated clone that persisted in the patient for more than 10 years despite treatment with intensive chemotherapy and allogeneic hematopoietic stem cell transplantation (alloHSCT). CASE PRESENTATION: A 42-year-old male was diagnosed with AML harboring a normal karyotype and mutations in the NPM1 (c.863_864ins, p.W288 fs*12), DNMT3A (c.2645G > A, p.R882H), and IDH1 (c.395G > A, p.R132H) genes. He achieved complete remission with intensive chemotherapy and was subsequently submitted to alloHSCT. Eleven years later, he was given chemotherapy and radiotherapy to treat a lung carcinoma. Three years later, t-AML was diagnosed; the disease had arisen from a pre-existing DNMT3A mutated patient-origin clone that had subsequently acquired a TP53 mutation and a complex karyotype. Although a second transplantation was intended, the disease was refractory to induction chemotherapy, and the patient eventually died from disease complications. We retrospectively demonstrated the persistence and post-transplantation latency of the R882H-DNMT3A mutation using a real-time PCR allele-specific analysis at different time-points during the observation period. DISCUSSION AND CONCLUSION: The present case highlights the potential clinical implications of a R882H-DNMT3A mutated clone that persisted after conventional AML treatment, including alloHSCT. It also reinforces the notion of the importance of cell non-intrinsic factors, such as the hematopoietic-stress induced by chemotherapy and radiotherapy, as drivers of clonal expansion.

Primary prophylaxis of invasive fungal infections with posaconazole or itraconazole in patients with acute myeloid leukaemia or high-risk myelodysplastic syndromes undergoing intensive cytotoxic chemotherapy: A real-world comparison.

This is an observational-retrospective study comparing the real-world outcomes associated with posaconazole vs itraconazole as prophylaxis treatments. Two hundred and ninety-three patient admissions attributable to 174 patients were included in the study. Patients were treated with itraconazole (n = 114 admissions; 39%) or posaconazole (n = 179; 61%). Antifungal prophylaxis failure (APF) due to treatment-related adverse events (in 34 out of 293 patient admissions; 11.6%) was more frequent in the posaconazole group (6.1% vs 15.1%; P = .024). There were 9 patient admissions for episodes of APF due to probable/proven breakthrough fungal infection (primary endpoint): 6 and 3 in the itraconazole and posaconazole group respectively (5.3% vs 1.7%; P = .095). All of them were associated with invasive pulmonary aspergillosis (IPA). APF was more frequent with itraconazole (65% vs 30%; P < .001), along with failure due to possible/probable/proven IPA (25% vs 10%; P = .002) and overall failure by any of the 3 different causes of prophylaxis failure (70% vs 38%; P < .001). In agreement with clinical trial data, this real-world evidence supports the use of posaconazole over itraconazole in AML or MDS patients undergoing intensive chemotherapy.

IL28B genetic variation and cytomegalovirus-specific T-cell immunity in allogeneic stem cell transplant recipients.

A single nucleotide polymorphism (SNP), 3 kbp upstream of the IL28B gene (rs12979860; C/T), has been shown to influence the dynamics of cytomegalovirus (CMV) replication in allogeneic stem cell transplant recipients (Allo-SCT). We investigated whether this SNP had any effect on the dynamics of CMV-specific T-cell immunity in these patients. CMV pp65/IE-1 IFN-γ CD8+ and CD4+ T cells were enumerated by flow cytometry in 85 patients with no prior CMV DNAemia (group A) and in 57 after the onset of CMV DNAemia (group B). Donor IL28B genotype was determined by real-time PCR and plasma levels of IL-28B were quantitated by ELISA. CMV-specific T-cell counts and plasma IL-28B levels in patients in group A were not significantly different among the IL28B genotype groups. Patients harboring the donor IL28B T/T genotype appeared to expand CMV-specific IFN-γ CD8+ cells to a higher level in response to viral replication than their C/T and C/C counterparts. Fewer patients in the T/T group received pre-emptive antiviral therapy (P = 0.05). Overall, a significant inverse correlation was observed between median IL-28B levels measured prior to the CMV DNAemia onset and the level of CMV-specific CD8+ T cells enumerated after detection of CMV DNAemia (σ = -0.471; P = 0.013). In summary, the data suggested that the protective effect attributed to the rs12979860 SNP minor T allele could be mediated, at least in part, by eliciting robust CMV-specific T-cell responses. J. Med. Virol. 89:685-695, 2017. © 2016 Wiley Periodicals, Inc.

Impact of cytomegalovirus DNAemia on overall and non-relapse mortality in allogeneic stem cell transplant recipients.

BACKGROUND: We conducted a retrospective single-center study to investigate the potential impact of cytomegalovirus (CMV) DNAemia on mortality in allogeneic stem cell transplant (allo-SCT) recipients. METHODS: A total of 151 consecutive patients who underwent T-cell replete allo-SCT were included in the study. Patients with CMV DNAemia were treated preemptively with antivirals upon detection of plasma CMV DNA loads >1500 IU/mL. RESULTS: At least one episode of CMV DNAemia occurred in 109 (72.2%) patients, and 67 of these patients (61.5%) required one or more courses of antiviral therapy. The cumulative incidence of 1-year overall and non-relapse mortality (NRM) was 28.5% (95% confidence interval [CI], 18.4%-39.5%) and 23.2% (95% CI 12.81%-35.4%), respectively. The occurrence of either CMV DNAemia or CMV recurrences had no apparent effect on 1-year overall mortality and NRM; nevertheless, a trend towards an increased risk of death was seen in patients with one or more episodes of CMV DNAemia requiring antiviral therapy (hazard ratio [HR], 2.10; 95% CI, 0.96-4.61; P=.06 for overall mortality, and HR, 2.36; 95% CI, 0.96-5.76; P=.06 for NRM) but not in those displaying one or more self-resolving episodes. CONCLUSION: Therefore, the data suggest that withholding preemptive antiviral therapy until the plasma CMV DNA load reaches 1500 IU/mL has no apparent detrimental effect on patient survival.

Risk factors for non-melanoma skin cancer in patients with essential thrombocythemia and polycythemia vera.

OBJECTIVES: Population-based studies have reported an increased incidence of skin cancer in patients with essential thrombocythemia (ET) and polycythemia vera (PV). We have examined the risk factors for non-melanoma skin cancer (NMSC) in patients diagnosed with ET or PV during 1973-2012. METHODS: A case-control study was performed to compare the clinical and treatment-related data of 51 ET/PV patients who had NMSC with that of 401 patients who did not. We also evaluated whether polymorphisms in 12 genes involved in DNA integrity predisposed to NMSC. RESULTS: By multivariate logistic regression analysis, risk factors for NMSC were older age (OR: 1.7, 95% CI: 1.3-2.1, P < 0.001), male sex (OR: 2.1, 95% CI: 1.1-3.8, P = 0.023), higher cumulated hydroxycarbamide dose (OR: 1.3, 95% CI: 1.1-1.7, P = 0.017), and busulphan exposure (OR: 3.2, 95% CI: 1.05-10.0, P = 0.041). On the time-to-event prognostic model, factors independently associated with increased cumulative incidence of NMSC were age (5% increased risk per year; P < 0.001), male sex (91% increased risk; P = 0.022), and hydroxycarbamide exposure (22% increased risk; P = 0.065). No susceptibility gene variant was identified. CONCLUSIONS: These findings suggest that the risk to develop NMSC in ET/PV patients results from the combined effect of common risk factors (age, male sex) together with cytoreductive treatment.

Lack of evidence for a reciprocal interaction between bacterial and cytomegalovirus infection in the allogeneic stem cell transplantation setting.

Pathogenic interactions between bacteria and cytomegalovirus (CMV) may potentially occur early after allogeneic stem cell transplantation (allo-SCT). This possibility nevertheless has not been investigated in depth. This was a retrospective study that included 170 consecutive patients who underwent 173 allo-SCTs. Both bacterial infection (most of which were bacteremic) and CMV DNAemia were detected in 78 allo-SCTs (62.9%). In total, 51 and 32 episodes of bacterial infection preceded or occurred after CMV DNAemia detection, respectively. Both events were diagnosed concurrently in four allo-SCTs. The cumulative incidence of bacterial infection (of any type) over the study period was comparable in patients with or without a preceding episode of CMV DNAemia (P = 0.321). Cox proportional hazards regression analysis failed to identify CMV DNAemia as a significant risk factor for bacterial infection. Likewise, the cumulative incidence of CMV DNAemia within the study period was not significantly different in patients with or without a preceding episode of bacterial infection (P = 0.189). Furthermore, the occurrence of bacterial infection within episodes of active CMV infection had no apparent impact on the kinetics of CMV DNAemia. Our data, thus, do not support the existence of a bidirectional synergistic effect between bacterial infection and active CMV infection in the allo-SCT setting.

Plasma metabolomics profiling for the prediction of cytomegalovirus DNAemia and analysis of virus­host interaction in allogeneic stem cell transplant recipients.

Metabolomics analysis of biofluids is increasingly being recognized as a useful tool for the diagnosis and management of a number of infectious diseases. Here we showed that plasma metabolomics profiling by untargeted 1H nuclear magnetic resonance may allow the anticipation of the occurrence of cytomegalovirus (CMV) DNAemia in allogeneic stem cell transplant. For this purpose, key discriminatory metabolites were total glutathione, taurine, methylamine, trimethylamine N-oxide and lactate, all of which were upregulated in patients eventually developing CMV DNAemia. The overall classification accuracy (predictability) of the projection to latent structure discriminant analysis (PLS-DA) model in cross-validation technical replicates was 73 %. Increased levels of alanine, lactate and total fatty acids, and a shift in the fatty acid profile towards unsaturated species, were observed in patients with detectable CMV DNA in plasma. The classification accuracy of this PLS-DA model in cross-validation technical replicates was 81 %. Plasma metabolomics profiling may prove useful for identifying patients at highest risk for CMV DNAemia thus allowing early inception of antiviral therapy.

Role of cytomegalovirus (CMV)-specific polyfunctional CD8+ T-cells and antibodies neutralizing virus epithelial infection in the control of CMV infection in an allogeneic stem-cell transplantation setting.

The role of cytomegalovirus (CMV)-specific polyfunctional CD8+ T-cells and that of antibodies neutralizing virus epithelial infection (AbNEI) in the control of CMV DNAemia were investigated in 39 CMV-seropositive allogeneic stem-cell transplant (Allo-SCT) recipients with (n = 24) or without (n = 15) CMV DNAemia. AbNEI levels were monitored prospectively by means of a neutralization assay employing retinal epithelial cells (ARPE-19) and the recombinant CMV strain BADrUL131-Y4. Quantification of CMV-specific polyfunctional CD8+ T-cells (expressing two or three of the following markers: IFN-γγ, TNF-α and CD107a) in whole blood was performed by flow cytometry for intracellular cytokine staining. We found no differences in the dynamic pattern of AbNEI in patients with or without subsequent CMV DNAemia. Baseline and peak AbNEI titres were not predictive of the dynamics of CMV replication within episodes. No correlation was found between CMV DNA loads and AbNEI levels during episodes of CMV DNAemia (ρ = 0.09; 95 % confidence interval - 0.52 to 0.64; P = 0.78). The detection of pp65/IE-1 CMV-specific polyfunctional CD8+ T-cells was associated with low-level virus replication within subsequent episodes of CMV DNAemia. Interestingly, the presence of AbNEI titres (inverse) >4.7 log2 was predictive of the occurrence of CMV DNAemia (sensitivity, 83 %; specificity, 80 %). Our findings provide an insight to the role of humoral and cellular immunity in the control of CMV infection in an Allo-SCT setting.

Incidence and dynamics of active cytomegalovirus infection in allogeneic stem cell transplant patients according to single nucleotide polymorphisms in donor and recipient CCR5, MCP-1, IL-10, and TLR9 genes.

Single nucleotide polymorphisms (SNPs) in genes involved in the activation or regulation of innate and adaptive immune responses may modulate the susceptibility to and the natural history of certain chronic viral infections. The current study aimed to investigate whether donor and recipient SNPs in the chemokine receptor 5 (rs1800023), monocyte chemoattractant protein 1 (rs13900), interleukin-10 (rs1878672), and Toll-like receptor 9 (rs352140) genes would exert any influence on the rate of incidence and features of CMV DNAemia in the allogeneic stem cell transplantation setting. This was a retrospective observational multicenter study. The cohort consisted of 102 non-consecutive allogeneic stem cell transplant recipients. SNP genotyping was performed by allele-specific real-time PCR. CMV surveillance was performed by the pp65 antigenemia assay/and or by real-time PCR. Seventy-three patients developed CMV DNAemia within the first 100 days after transplantation (71.5%). Neither donor nor recipient SNPs were associated significantly with the rate of incidence of active CMV infection, nor with the need for pre-emptive antiviral therapy. Both the duration of CMV DNAemia and the plasma CMV DNA peak load during episodes were significantly higher in patients harboring the donor (but not the recipient) chemokine receptor 5 A/A genotype, than in their A/G and G/G counterparts (P = 0.022 and P = 0.045, respectively). The data reported suggest that SNPs in chemokine receptor 5 may influence the dynamics of CMV infection in the Allo-SCT setting.

Enumeration of NKG2C+ natural killer cells early following allogeneic stem cell transplant recipients does not allow prediction of the occurrence of cytomegalovirus DNAemia.

The role of Natural killer (NK) cells in the control of cytomegalovirus (CMV) infection in allogeneic stem cell transplant recipients has not been precisely characterized. The current study is aimed at investigating the potential role of NK cells expressing the activating receptor NKG2C in affording protection against the development of CMV DNAemia in patients exhibiting detectable CMV-specific CD8(+) T-cell responses early following transplantation. A total of 61 nonconsecutive patients were included in the study. Peripheral levels of CD56(bright) CD16(-/low) and CD56(dim) CD16(+) NKG2C(+) NK cells and CMV pp65/IE-1-specific IFN-γ-producing CD8(+) T-cells were enumerated by flow cytometry at days +30 and +60 after transplant. Neither the absolute number of NKG2C(+) NK cells, nor that of CD56(bright) CD16(-/low) and CD56(dim) CD16(+) NKG2C(+) NK-cell subsets at day 30 differed significantly between patients with or without subsequent CMV DNAemia. No significant correlation was found between levels of both NKG2C(+) NK-cell populations and the peak CMV DNA load within subsequent episodes of CMV DNAemia. The data indicate that enumeration of NKG2C(+) NK cells early after transplant is unlikely to be helpful in identifying those patients at highest risk of developing CMV DNAemia. Moreover, the data do not support a direct implication of NKG2C(+) NK cells in preventing the development of CMV DNAemia.