Monitoring of CMV‐specific cell‐mediated immunity with a commercial ELISA‐based interferon‐γ release assay in kidney transplant recipients treated with antithymocyte globulin

Monitoring for cytomegalovirus (CMV)‐specific cell‐mediated immunity (CMV‐CMI) may be useful for individualizing valganciclovir (VGCV) prophylaxis after kidney transplantation (KT). We performed a commercial ELISA‐based interferon (IFN)‐γ release assay (QTF‐CMV) from posttransplant months 2‐5 (362 points) in 120 CMV‐seropositive KT recipients that received antithymocyte globulin as induction therapy and VGCV prophylaxis (median of 92 days). Forty‐seven patients (39.3%) had CMV infection after discontinuation of prophylaxis. The QTF‐CMV assay was reactive, nonreactive, and indeterminate in 264 (72.9%), 90 (24.9%), and 8 points (2.2%). The QTF‐CMV assay at prophylaxis discontinuation exhibited suboptimal accuracy for predicting protective CMV‐CMI (sensitivity: 77.4%; specificity: 34.3%; positive predictive value [PPV]: 64.1%; negative predictive value [NPV]: 50.0%), with no differences in 1‐year CMV infection rates between patients with negative (nonreactive or indeterminate) or reactive results (45.8% vs 36.1%; P = .244). Specificity and PPV to predict protective CMV‐CMI improved by elevating the IFN‐γ cutoff value to 1.13 IU/mL (65.7% and 71.4%) and 7.0 IU/mL (85.7% and 76.2%), although NPVs decreased. The QTF‐CMV assay as per manufacturer's interpretative criteria performed poorly to predict protection from CMV infection following discontinuation of VGCV prophylaxis among ATG‐treated CMV‐seropositive KT recipients. This performance is slightly improved by modifying the IFN‐γ positivity threshold.     

CMV‐specific T‐cell immunity,viral load,and clinical outcome in seropositive renal transplant recipients: a pilot study

Sund F, Lidehäll A‐K, Claesson K, Foss A, Tötterman TH, Korsgren O, Eriksson B‐M. CMV‐specific T‐cell immunity, viral load, and clinical outcome in seropositive renal transplant recipients: a pilot study.
Clin Transplant 2010: 24: 401–409. © 2009 Wiley Periodicals, Inc. Abstract: Background: Cytomegalovirus (CMV) infection is still the leading opportunistic infection following solid organ transplantation. The aim of this prospective study of renal transplant recipients was to evaluate the dynamics of CMV‐specific T‐cells, viral load, and clinical symptoms of CMV infection. Methods: Levels of tetramer‐selected CD8⁺ T‐cells (TetraCD8), CMV‐specific interferon‐γ producing CD8⁺ T‐cells (IFNγCD8), and CD4⁺ T‐cells (IFNγCD4), measured using major histocompatibility complex‐tetramer and cytokine flow cytometry techniques, and CMV DNA were monitored monthly in 17 CMV‐seropositive patients up to one yr (median 12 months, range 3–12) after transplantation and correlated to clinical outcome. Results: CMV DNAemia was detected in 94% of the patients, but only one patient developed CMV disease. CMV DNAemia >1 million copies/mL was seen in asymptomatic patients. CMV‐specific T‐cells decreased rapidly after transplantation. TetraCD8 and IFNγCD8 regenerated within three months, whereas IFNγCD4 recovery was impaired up to one yr after transplantation. The proportion of IFNγCD4 at two months post‐transplantation as compared with baseline, correlated strongly with the magnitude of the CMV DNAemia. Conclusions: Monitoring the reduction of IFNγCD4 compared with baseline during the first months after transplantation could be considered in predicting risk for high‐grade CMV DNAemia and in deciding strategic approaches for pre‐emptive and prophylactic therapy.     

A prospective multicenter observational study of cell‐mediated immunity as a predictor for cytomegalovirus infection in kidney transplant recipients

T cell immunity is essential for the control of cytomegalovirus (CMV) infection after transplantation. We evaluated a CMV‐specific peptide‐based enzyme‐linked immunosorbent spot (ELISPOT) assay to determine whether assay results could predict subsequent CMV events. Adult kidney transplant recipients at 43 centers underwent ELISPOT testing to enumerate interferon gamma (IFN‐γ) binding spot‐forming units (sfu) after stimulation of cells with an overlapping peptide pool of CMV phosphoprotein 65 (pp65) and immediate early‐1 (IE‐1) protein at the end of antiviral prophylaxis (EOP) and various time points thereafter. The primary outcome was a CMV event in the first posttransplant year. In 583 kidney transplant recipients (260 seropositive donor [D+]/seronegative recipient [R?] and 277 R+), CMV events occurred in 44 of 368 eligible patients (11.8%) at a median of 227 days (range 92‐360) posttransplant. A cutoff value of >40 sfu/2.5 × 10⁵ cells for either IE‐1 or pp65 was derived as a threshold for positivity, with a negative predictive value of >97% for CMV events. CMV events were significantly lower in assay positive vs assay negative patients (3.0% vs 19.5%, P < .0001 for pp65). Time to CMV event post‐EOP was significantly greater in those with sfu >40 at EOP (P < .0001). In this large, multicenter trial of kidney transplant recipients, we show that an assessment of CMV‐specific immunity using a novel ELISPOT assay is able to predict protection from CMV infection.     

Pretransplant Interferon‐γ Secretion by CMV‐Specific CD8+ T Cells Informs the Risk of CMV Replication After Transplantation

In this prospective study we analyzed pretransplant interferon‐γ secretion by cytomegalovirus (CMV)‐specific CD8+ T cells to assess its possible utility in determining the risk of CMV replication after solid organ transplantation. A total of 113 lung and kidney transplant patients were enrolled in the study but only 55 were evaluable. All CMV‐seronegative recipients were pretransplant “nonreactive” (IFNγ <0.2 IU/mL) (11/11), whereas 30/44 (68.2%) CMV‐seropositive (R+) recipients were “reactive” (IFNγ ≥0.2 IU/mL) and 14/44 (31.8%) were “nonreactive”. In the R(+) “nonreactive” group, 7/14 (50%) developed posttransplant CMV replication, whereas the virus replicated only in 4/30 (13.3%) of the R(+) “reactive” patients (p = 0.021). According to the best multivariate model, pretransplant “nonreactive” recipients receiving an organ from a CMV‐seropositive donor had a 10‐fold increased risk of CMV replication compared to pretransplant “reactive” recipients (adjusted OR 10.49, 95% CI 1.88–58.46). This model displayed good discrimination ability (AUC 0.80) and calibration (Hosmer–Lemeshow test, p = 0.92). Negative and positive predictive values were 83.7% and 75%, respectively. The accuracy of the model was 82%. Therefore, assessment of interferon‐γ secretion by cytomegalovirus (CMV)‐specific CD8+ T cells prior to transplantation is useful in informing the risk of posttransplant CMV replication in solid organ transplant patients.     

Blood dendritic cell levels associated with impaired IL‐12 production and T‐cell deficiency in patients with kidney disease: implications for post‐transplant viral infections

Reduced pretransplant blood myeloid dendritic cell (mDC) levels are associated with post‐transplant BK viremia and cytomegalovirus (CMV) disease after kidney transplantation. To elucidate potential mechanisms by which mDC levels might influence these outcomes, we studied the association of mDC levels with mDC IL‐12 production and T‐cell level/function. Peripheral blood (PB) was studied in three groups: (i) end stage renal disease patients on hemodialysis (HD; n = 81); (ii) chronic kidney disease stage IV‐V patients presenting for kidney transplant evaluation or the day of transplantation (Eval/Tx; n = 323); and (iii) healthy controls (HC; n = 22). Along with a statistically significant reduction in mDC levels, reduced CD8⁺ T‐cell levels were also demonstrated in the kidney disease groups compared with HC. Reduced PB mDC and monocyte‐derived DC (MoDC) IL‐12 production was observed after in vitro LPS stimulation in the HD versus HC groups. Finally, ELISpot assays demonstrated less robust CD3⁺ INF‐γ responses by MoDCs pulsed with CMV pp65 peptide from HD patients compared with HC. PB mDC level deficiency in patients with kidney disease is associated with deficient IL‐12 production and T‐cell level/function, which may explain the known correlation of CD8⁺ T‐cell lymphopenia with deficient post‐transplant antiviral responses.     

Association of high IFN‐γ plasma levels with low B‐cell counts in renal transplant recipients with stable long‐term graft function

Daniel V, Naujokat C, Sadeghi M, Renner FC, Weimer R, Opelz G. Association of high IFN‐γ plasma levels with low B‐cell counts in renal transplant recipients with stable long‐term graft function.
Clin Transplant 2009 DOI: 10.1111/j.1399‐0012.2009.01067.x
© 2009 John Wiley & Sons A/S. Abstract: Recently, we reported that patients with long‐term stable good graft function had higher interferon‐gamma (IFN‐γ) and lower IL‐4 plasma levels late as compared with early post‐transplant. These patients had more often detectable CD3⁺CD4⁺CD25⁺IFN‐γ⁺Foxp3⁺ peripheral blood lymphocytes (PBL) late post‐transplant than patients with impaired graft function. We therefore speculated that high plasma IFN‐γ late post‐transplant might contribute to the maintenance of graft acceptance. Using ELISA and four‐color flow cytometry, plasma cytokines and PBL subpopulations were measured in 65 renal transplant recipients with stable graft function late post‐transplant. High IFN‐γ plasma levels were associated with low CD19⁺ B PBL (r = ?0.329; p = 0.009) and low activated CD3⁺CD8⁺DR⁺ T PBL (r = ?0.266; p = 0.035). Plasma IFN‐γ increased with time post‐transplant (r = 0.288; p = 0.022) and was not associated with the dose of immunosuppressive drugs (p = n.s.). High plasma IFN‐γ was not associated with serum creatinine (r = 0.038; p = 0.765). Five patients showed evidence of chronic allograft nephropathy in previous biopsies and none of them exhibited increased plasma IFN‐γ. In patients with good long‐term graft function, high IFN‐γ plasma levels were associated with low numbers of B PBL and activated CD8⁺ T PBL. High IFN‐γ plasma levels might prevent the development of an immunological alloresponse and thereby contribute to the maintenance of graft acceptance.     

Development of immune response to tissue‐restricted self‐antigens in simultaneous kidney‐pancreas transplant recipients with acute rejection

Simultaneous kidney‐pancreas transplantation (SKP Tx) is a treatment for end‐stage kidney disease secondary to diabetes mellitus. We investigated the role of immune responses to donor human leukocyte antigens (HLA) and tissue‐restricted kidney and pancreas self‐antigens (KSAgs and PSAgs, respectively) in SKP Tx recipients (SKP TxRs). Sera collected from 39 SKP TxRs were used to determine de novo Abs specific for KSAgs (collagen‐IV, Col‐IV; fibronectin, FN) and PSAgs (insulin, islet cells, glutamic acid decarboxylase, and pancreas‐associated protein‐1) by ELISA. KSAg‐specific IFN‐γ, IL‐17, and IL‐10 cytokines were enumerated by ELISpot. Abs to donor HLA classes I and II were determined by Luminex assay. Abs to KSAgs and PSAgs were detectable in recipients with rejection compared with stable recipients (P<.05). Kidney‐only rejection recipients had increased Abs against KSAgs compared with stable (P<.05), with no increase in Abs against PSAgs. Pancreas‐only rejection recipients showed increased Abs against PSAgs compared to stable (P<.05), with no Abs against KSAgs. SKP TxRs with rejection showed increased frequencies of KSAg‐specific IFN‐γ and IL‐17 with reduction in IL‐10‐secreting cells. SKP TxRs with rejection developed Abs to KSAgs and PSAgs demonstrated increased frequencies of kidney or pancreas SAg‐specific IFN‐γ and IL‐17‐secreting cells with reduced IL‐10, suggesting loss of peripheral tolerance to SAgs.     

High‐Quality CMV‐Specific CD4+ Memory Is Enriched in the Lung Allograft and Is Associated With Mucosal Viral Control

The maintenance of CMV‐specific T cell memory in lung transplant recipients (LTRs) is critical for host defense and allograft durability, particularly in donor⁺/recipient^? (D⁺R^?) individuals who demonstrate increased mortality. We studied CD4⁺ and CD8⁺ CMV‐specific memory responses to phosphoprotein 65 (pp65) in a prospective cohort of 18 D⁺R^? LTRs, from bronchoalveolar lavage (BAL)‐obtained lung mononuclear cells (LMNC) and PBMC. Unexpectedly, pp65‐specific CD4⁺ and CD8⁺ IFN‐γ memory responses from LMNC were similar, in contrast to persistent CD8⁺ predominance in PBMC. Unlike the pulmonary CD8⁺ predominance during acute primary infection, compartmental equalization occurred in the CMV‐specific CD8⁺ memory pool during chronic infection, whereas CMV‐specific CD4⁺ memory was enriched in the bronchoalveolar space. Moreover, CMV‐specific CD4⁺ memory T cells with multifunctional production of IFN‐γ, TNF‐α, IL‐2 and MIP‐1β were significantly increased in LMNCs, in contrast to similar intercompartmental CD8⁺ memory function. Moreover, the absolute number of CMV‐specific CD4⁺IFN‐γ⁺ memory cells in BAL was significantly increased in LTRs exhibiting viral control compared to those with CMV early antigen positivity. Collectively, these data demonstrate both preferential distribution and functional quality of CMV‐specific CD4⁺ memory in the lung allograft during chronic infection, and show an important association with CMV mucosal immunity and viral control.     

Cytomegalovirus‐Responsive CD8+ T Cells Expand After Solid Organ Transplantation in the Absence of CMV Disease

Cytomegalovirus (CMV) is a major cause of morbidity and mortality in solid organ transplant recipients. Approximately 60% of adults are CMV seropositive, indicating previous exposure. Following resolution of the primary infection, CMV remains in a latent state. Reactivation is controlled by memory T cells in healthy individuals; transplant recipients have reduced memory T cell function due to chronic immunosuppressive therapies. In this study, CD8⁺ T cell responses to CMV polypeptides immediate‐early‐1 and pp65 were analyzed in 16 CMV‐seropositive kidney and heart transplant recipients longitudinally pretransplantation and posttransplantation. All patients received standard of care maintenance immunosuppression, antiviral prophylaxis, and CMV viral load monitoring, with approximately half receiving T cell–depleting induction therapy. The frequency of CMV‐responsive CD8⁺ T cells, defined by the production of effector molecules in response to CMV peptides, increased during the course of 1 year posttransplantation. The increase commenced after the completion of antiviral prophylaxis, and these T cells tended to be terminally differentiated effector cells. Based on this small cohort, these data suggest that even in the absence of disease, antigenic exposure may continually shape the CMV‐responsive T cell population posttransplantation.     

CMV‐infected kidney grafts drive the expansion of blood‐borne CMV‐specific T cells restricted by shared class I HLA molecules via presentation on donor cells

We aimed to determine the role of cytomegalovirus (CMV)‐infected donor cells in the development of a CMV‐specific immune response in kidney transplant recipients. We assessed the CMV pp65‐specific immune response by using interferon‐? ELISPOT and dextramers in peripheral blood mononuclear cells from 115 recipients (D+R? 31, D+R + 44, D?R + 40) late after transplantation (mean 59 ± 42 months). Receiving a kidney from a D+ donor resulted in a higher number of IFN‐?‐producing anti‐CMV T cells (P = .004). This effect disappeared with the absence of shared HLA class I specificities between donors and recipients (P = .430). To confirm the role of donor cells in stimulating the expansion of newly developed CMV‐specific CD8⁺ T cells after transplantation, we compared the number of HLA‐A2–restricted CMV‐specific CD8⁺ T cells in primo‐infected recipients who received an HLA‐A2 or non–HLA‐A2 graft. The median of anti‐CMV pp65 T cells restricted by HLA‐A2 was very low for patients who received a non–HLA‐A2 graft vs an HLA‐A2 graft (300 [0‐14638] vs. 17972 [222‐85594] anti‐CMV pp65 CD8⁺ T cells/million CD8⁺ T cells, P = .001). This adds new evidence that CMV‐infected kidney donor cells present CMV peptides and drive an inflation of memory CMV‐specific CD8⁺ T cells, likely because of frequent CMV replications within the graft.     

Pretransplant Immediately Early‐1‐Specific T Cell Responses Provide Protection for CMV Infection After Kidney Transplantation

Cytomegalovirus (CMV) infection is still a major complication after kidney transplantation. Although cytotoxic CMV‐specific T cells play a crucial role controlling CMV survival and replication, current pretransplant risk assessment for CMV infection is only based on donor/recipient (IgG)‐serostatus. Here, we evaluated the usefulness of monitoring pre‐ and 6‐month CMV‐specific T cell responses against two dominant CMV antigens (IE‐1 and pp65) and a CMV lysate, using an IFN‐γ Elispot, for predicting the advent of CMV infection in two cohorts of 137 kidney transplant recipients either receiving routine prophylaxis (n = 39) or preemptive treatment (n = 98). Incidence of CMV antigenemia/disease within the prophylaxis and preemptive group was 28%/20% and 22%/12%, respectively. Patients developing CMV infection showed significantly lower anti‐IE‐1‐specific T cell responses than those that did not in both groups (p < 0.05). In a ROC curve analysis, low pretransplant anti‐IE‐1‐specific T cell responses predicted the risk of both primary and late‐onset CMV infection with high sensitivity and specificity (AUC > 0.70). Furthermore, when using most sensitive and specific Elispot cut‐off values, a higher than 80% and 90% sensitivity and negative predictive value was obtained, respectively. Monitoring IE‐1‐specific T cell responses before transplantation may be useful for predicting posttransplant risk of CMV infection, thus potentially guiding decision‐making regarding CMV preventive treatment.     

Natural Killer Cell Receptor Repertoire and Their Ligands,and the Risk of CMV Infection After Kidney Transplantation

Cytomegalovirus (CMV) infection is the most common viral complication after solid organ transplantation (SOT). Whilst current immunosuppression is known to impair antiviral‐specific T‐cell immunity in SOT, a potential role for natural killer (NK) cells not affected by immunosuppressive therapy remains to be determined. To address this, we compared the genotype of the NK immunoglobulin‐like receptor (KIR) genes and their HLA cognate ligands to the rate of CMV infection in 196 kidney transplant recipients. We have shown that the absence of the HLA‐C ligand for inhibitory KIR and the presence of activating KIR genes in the recipients were both associated with a lower rate of CMV infection after transplantation. In a cohort of 17 recipients with acute CMV infection, NK cells were phenotyped over a period of time after diagnosis by their expression profile of C‐type lectin receptors and capacity to secrete IFN‐γ. The increased expression of the activating C‐type lectin receptors NKG2C and NKG2D was paralleled by the decreased IFN‐γ secretion during the early phase of CMV infection. In conclusion, our findings suggest that KIR/HLA genotype and expression of NKG2C and NKG2D might play a significant role in regulating NK cell function and anti‐CMV immunity after kidney transplantation.     

Cytomegalovirus (CMV) DNA quantification in bronchoalveolar lavage fluid of immunocompromised patients with CMV pneumonia

Cytomegalovirus (CMV) pneumonia causes major morbidity and mortality. Its diagnosis requires demonstration of viral cytopathic changes in tissue, entailing risks of lung biopsy. This study aimed to determine CMV viral load (VL) thresholds in bronchoalveolar lavage fluid (BALF) for diagnosis of CMV pneumonia in immunocompromised patients. CMV VL in BALF was studied in 17 patients (83% transplant recipients) and 21 control subjects with and without CMV pneumonia, respectively, using an FDA‐approved PCR assay (Cobas^® AmpliPrep/Cobas TaqMan^® CMV Test, Roche Molecular Systems, Inc.) calibrated to the WHO International Standard for CMV DNA (NIBSC: 09/162). Receiver operating characteristic curve analysis produced a BALF CMV VL threshold of 34 800, IU/mL with 91.7% sensitivity and 100.0% specificity for diagnosis of possible, probable, and proven CMV pneumonia in transplant patients, while a threshold of 656 000 IU/mL yielded 100% sensitivity and specificity among biopsy‐proven cases. For all immunocompromised patients, a VL threshold of 274 IU/mL was selected. VL thresholds also were normalized to BALF cell count yielding a threshold of 0.32 IU/10⁶ cells with 91.7% sensitivity and 90.5% specificity for possible, probable, and proven CMV pneumonia in transplant recipients. Monitoring CMV VL in BALF may be a less invasive method for diagnosing CMV pneumonia in immunocompromised patients.     

Viral load,CMV‐specific T‐cell immune response and cytomegalovirus disease in solid organ transplant recipients at higher risk for cytomegalovirus infection during preemptive therapy

Despite advances in prevention, cytomegalovirus (CMV) recurrence is an important challenge in high‐risk organ recipients. The present study prospectively evaluates the impact of CMV‐specific T‐cell immune response and secondary prophylaxis on the risk of recurrence in a cohort of CMV high‐risk organ recipients and whether it is possible to determine a safe standardized viral load value below which CMV disease is unlikely. Thirty‐nine recipients were included. Thirty‐six had primary infections, and 88.9% recurred. Rate and duration of recurrent CMV infection was similar in patients with and without secondary prophylaxis: 57.9% vs. 53.6%, P = 0.770 and 16 vs. 15 days, P = 0.786, respectively. The only factor independently associated with no episodes of CMV recurrence was the acquisition of CMV‐specific T‐cell immune response (OR: 0.151, 95% CI: 0.028–0.815; P = 0.028). Cytomegalovirus diseases (N = 5) occurred in patients with CMV viral load above 1500 IU/ml who did not follow the planned monitorization schedule. Our observations suggest that episodes of recurrent CMV infection are common after preemptive therapy despite secondary prophylaxis and that CMV‐specific T‐cell immune response is associated with a decreased risk of recurrent infections. Preemptive therapy may be safe in patients at high risk for CMV infection with strict close monitoring of the CMV viral load.     

Effets du cytomégalovirus en transplantation et place de la prophylaxie antivirale

Cytomegalovirus (CMV) belongs to β-Herpesviridae family. Morbidity related to this infectious agent remains a serious concern in the context of immunosuppression. Occurence of CMV infection within the first 3 months post-renal transplantation without any antiviral prophylaxis is about 70% of patients. Direct and indirect effects of CMV infection in the setting of organ transplantation are described in this review. A 3 to 6 months course of prophylaxis with valganciclovir is advised concerning high-risk transplant recipients (D+/R?) but recommendation regarding intermediate-risk transplant recipients (CMV-seropositive patients) is still unclear. Recent studies highlight a benefit of long time prophylaxis (until 6 months) in terms of CMV disease occurence among D+/R? patients. News assays that measures IFNγ responses to a variety of CMV epitopes (Quantiferon^® and Elispot IFNγ) are developped to predict CMV disease onset after discontinuation of antiviral prophylaxis. These assays could contribute to adapt prophylaxis to each recipient.     

Role of BK virus infection in end‐stage renal disease patients waiting for kidney transplantation – viral replication dynamics from pre‐ to post‐transplant

We report the prevalence of BK virus (BKV) infection before renal transplantation and the dynamics of BKV viremia from pre‐ to post‐transplantation. We assessed 60 kidney transplanted patients from a single cohort in Italy, treated with identical immunosuppressive therapy, for BK viremia at pre‐transplantation, 12 h, and three and six months post‐transplantation. Polymerase chain reaction showed that the prevalence of plasma BKV replication – considered a marker of infection – was 20% in pre‐transplant patients. All pre‐transplant‐positive patients remained positive post‐transplant, whereas the majority of pre‐transplant‐negative patients remained negative. Viremia dynamics classification revealed three clusters of patients: Cluster A++, pre‐transplant‐positive patients (20%) who tested positive at least once post‐transplant; Cluster B?+, pre‐transplant‐negative patients (28%) who tested positive at least once post‐transplant; and Cluster C– –, pre‐transplant‐negative patients (52%) who remained negative throughout. These clusters presented significant differences related to the prevalence of substantially positive patients with high plasma viral load (>10³ copies/mL) in cluster A, but not in donors’ or grafts’ characteristics. We suggest that pre‐transplant viral status should be considered as an additional risk factor for post‐transplant BKV replication. Therefore, pre‐transplant BKV infection screening in kidney transplant patients should be performed for improving planning of personalized immunosuppressant schemes and specific post‐transplant surveillance.     

Infections after kidney transplantation. Does age matter?

Infections threaten successful outcomes after kidney transplantation. Our aim was to determine if the number, types of infections and the risk factors for common infections differed between older compared to younger kidney transplant (KT) recipients in the first year after surgery. We performed a single‐center retrospective cohort study. Between 2011 and 2015, 91 KTs were performed in patients ≥65 years of age; these were matched 1:1 (by year of transplantation, sex and race) to controls aged 40‐60 years. Over 90% of both groups had an infectious complication. Urinary tract infections (UTIs) and cytomegalovirus (CMV) viremia were significantly more frequent in older recipients. Older adults had more late onset UTIs, including after stent removal. CMV viremia was more frequent in older adults in the 1‐6 months post‐transplant period. Due to our center‐specific protocol utilizing pre‐emptive monitoring in the CMV recipient‐seropositive population, the higher CMV incidence in the aged recipient was driven by this subpopulation of older adults. No difference in pneumonias or bloodstream infections were found, nor in surgical complications, rejection or graft loss. Mortality was higher at 1‐year post‐transplant in the older recipients (9.9% vs 1.1%; P = 0.018). Prophylactic and immunosuppressive strategies may need to be altered for older KT recipients.     

Non‐organ‐specific and anti‐endothelial antibodies in relation to CMV infection and acute rejection in renal transplant recipients

Costa C, Touscoz GA, Bergallo M, Terlizzi ME, Astegiano S, Sidoti F, Sinesi F, Segoloni GP, Cavallo R. Non‐organ‐specific and anti‐endothelial antibodies in relation to CMV infection and acute rejection in renal transplant recipients.
Clin Transplant 2010: 24: 488–492.
© 2009 John Wiley & Sons A/S. Abstract: The presence of non‐organ‐specific (NOSA) and anti‐endothelial antibodies (AECAs) and the onset of rejection in relation to cytomegalovirus (CMV) infection was investigated in 96 renal transplant recipients: 48 CMV pp65‐antigenemia‐negative (group 1) and 48 positive (group 2). The presence of autoantibodies (autoAbs) was evaluated before and following renal transplantation (first three months) by indirect immunofluoresce. Before transplantation, none of the patients was positive to AECAs, while eight (8.3%) were positive to NOSAs. Post‐transplantation, AECA were found in none of patients from group 1 vs. 15/48 (31.2%) from group 2 (p < 0.05); NOSAs were detected in 9/48 (18.8%) and 9/48 patients from group 1 and 2, respectively. An acute rejection was diagnosed in ten cases: six of interstitial type (antigenemia‐, and AECA‐negative; two NOSA‐positive); four of vascular type (all of them NOSA‐negative, 3/4 antigenemia‐, and AECA‐positive). CMV infection did not seem to be significantly associated with the appearance of NOSAs, while there was a significant correlation with the occurrence of AECAs. No significant correlation was found between acute rejection and the occurrence of NOSAs, while 75% of the cases of vascular rejection was associated to CMV infection and AECA‐positivity, suggesting the pathogenic role of CMV‐mediated endothelial damage.     

Timing of CMV‐specific effector memory T cells predicts viral replication and survival after allogeneic hematopoietic stem cell transplantation

The aim of this study was to characterize timing, kinetic, and magnitude of CMV‐specific immune response after hematopoietic stem cell transplantation (HSCT) and its ability to predict CMV replication and clinical outcomes. Using cell surface and intracellular cytokine staining by flow cytometry, CMV‐specific T‐cell response was measured in blood, while CMV viral load and chimerism were determined by real‐time PCR. Patients that reconstituted CMV‐specific T‐cell response within 6 weeks after Allo‐SCT showed a more robust immune response (CD8⁺: 0.7 cells/μl vs. 0.3/μl; P‐value = 0.01), less incidence of CMV replication (33% vs. 89.5%; P‐value = 0.007), reduced viral loads (1.81 log copies/ml vs. 0 copies/ml; P‐value = 0.04), and better overall survival (72%; CI: 0.53–0.96 vs. 42% CI: 0.24–0.71; P‐value = 0.07) than patients with a delayed immune reconstitution. Viremic patients had significantly higher transplant‐related mortality than nonviremic patients after 1 year (33% CI: 0.15–0.52 vs. 0% CI: 0.05–0.34; P‐value = 0.01). Risk factors independently associated with viral replication were receptor pretransplant CMV‐positive serostatus (P‐value = 0.02) and acquiring CMV‐specific T‐cell response after 6 weeks post‐transplantation (P‐value = 0.009). In conclusion, timing of acquiring a positive CMV‐specific T‐cell immune response after transplantation may identify patients with different risk for viral replication and different clinical outcomes, including survival.