Characterizing the risk of human leukocyte antigen-incompatible living donor kidney transplantation in older recipients.

Older compatible living donor kidney transplant (CLDKT) recipients have higher mortality and death-censored graft failure (DCGF) compared to younger recipients. These risks may be amplified in older incompatible living donor kidney transplant (ILDKT) recipients who undergo desensitization and intense immunosuppression. In a 25-center cohort of ILDKT recipients transplanted between September 24, 1997, and December 15, 2016, we compared mortality, DCGF, delayed graft function (DGF), acute rejection (AR), and length of stay (LOS) between 234 older (age ≥60 years) and 1172 younger (age 18-59 years) recipients. To investigate whether the impact of age was different for ILDKT recipients compared to 17 542 CLDKT recipients, we used an interaction term to determine whether the relationship between posttransplant outcomes and transplant type (ILDKT vs CLDKT) was modified by age. Overall, older recipients had higher mortality (hazard ratio: 1.632.072.65, P < .001), lower DCGF (hazard ratio: 0.360.530.77, P = .001), and AR (odds ratio: 0.390.540.74, P < .001), and similar DGF (odds ratio: 0.461.032.33, P = .9) and LOS (incidence rate ratio: 0.880.981.10, P = 0.8) compared to younger recipients. The impact of age on mortality (interaction P = .052), DCGF (interaction P = .7), AR interaction P = .2), DGF (interaction P = .9), and LOS (interaction P = .5) were similar in ILDKT and CLDKT recipients. Age alone should not preclude eligibility for ILDKT.

Center-level Variation in HLA-incompatible Living Donor Kidney Transplantation Outcomes.

BACKGROUND: Desensitization protocols for HLA-incompatible living donor kidney transplantation (ILDKT) vary across centers. The impact of these, as well as other practice variations, on ILDKT outcomes remains unknown. METHODS: We sought to quantify center-level variation in mortality and graft loss following ILDKT using a 25-center cohort of 1358 ILDKT recipients with linkage to Scientific Registry of Transplant Recipients for accurate outcome ascertainment. We used multilevel Cox regression with shared frailty to determine the variation in post-ILDKT outcomes attributable to between-center differences and to identify any center-level characteristics associated with improved post-ILDKT outcomes. RESULTS: After adjusting for patient-level characteristics, only 6 centers (24%) had lower mortality and 1 (4%) had higher mortality than average. Similarly, only 5 centers (20%) had higher graft loss and 2 had lower graft loss than average. Only 4.7% of the differences in mortality (P < 0.01) and 4.4% of the differences in graft loss (P < 0.01) were attributable to between-center variation. These translated to a median hazard ratio of 1.36 for mortality and 1.34 of graft loss for similar candidates at different centers. Post-ILDKT outcomes were not associated with the following center-level characteristics: ILDKT volume and transplanting a higher proportion of highly sensitized, prior transplant, preemptive, or minority candidates. CONCLUSIONS: Unlike most aspects of transplantation in which center-level variation and volume impact outcomes, we did not find substantial evidence for this in ILDKT. Our findings support the continued practice of ILDKT across these diverse centers.

Delayed graft function and acute rejection following HLA-incompatible living donor kidney transplantation.

Incompatible living donor kidney transplant recipients (ILDKTr) have pre-existing donor-specific antibody (DSA) that, despite desensitization, may persist or reappear with resulting consequences, including delayed graft function (DGF) and acute rejection (AR). To quantify the risk of DGF and AR in ILDKT and downstream effects, we compared 1406 ILDKTr to 17 542 compatible LDKT recipients (CLDKTr) using a 25-center cohort with novel SRTR linkage. We characterized DSA strength as positive Luminex, negative flow crossmatch (PLNF); positive flow, negative cytotoxic crossmatch (PFNC); or positive cytotoxic crossmatch (PCC). DGF occurred in 3.1% of CLDKT, 3.5% of PLNF, 5.7% of PFNC, and 7.6% of PCC recipients, which translated to higher DGF for PCC recipients (aOR = 1.03 1.682.72 ). However, the impact of DGF on mortality and DCGF risk was no higher for ILDKT than CLDKT (p interaction > .1). AR developed in 8.4% of CLDKT, 18.2% of PLNF, 21.3% of PFNC, and 21.7% of PCC recipients, which translated to higher AR (aOR PLNF = 1.45 2.093.02 ; PFNC = 1.67 2.403.46 ; PCC = 1.48 2.243.37 ). Although the impact of AR on mortality was no higher for ILDKT than CLDKT (p interaction = .1), its impact on DCGF risk was less consequential for ILDKT (aHR = 1.34 1.621.95 ) than CLDKT (aHR = 1.96 2.292.67 ) (p interaction = .004). Providers should consider these risks during preoperative counseling, and strategies to mitigate them should be considered.

Hospital readmissions following HLA-incompatible live donor kidney transplantation: A multi-center study.

Thirty percent of kidney transplant recipients are readmitted in the first month posttransplantation. Those with donor-specific antibody requiring desensitization and incompatible live donor kidney transplantation (ILDKT) constitute a unique subpopulation that might be at higher readmission risk. Drawing on a 22-center cohort, 379 ILDKTs with Medicare primary insurance were matched to compatible transplant-matched controls and to waitlist-only matched controls on panel reactive antibody, age, blood group, renal replacement time, prior kidney transplantation, race, gender, diabetes, and transplant date/waitlisting date. Readmission risk was determined using multilevel, mixed-effects Poisson regression. In the first month, ILDKTs had a 1.28-fold higher readmission risk than compatible controls (95% confidence interval [CI] 1.13-1.46; P < .001). Risk peaked at 6-12 months (relative risk [RR] 1.67, 95% CI 1.49-1.87; P < .001), attenuating by 24-36 months (RR 1.24, 95% CI 1.10-1.40; P < .001). ILDKTs had a 5.86-fold higher readmission risk (95% CI 4.96-6.92; P < .001) in the first month compared to waitlist-only controls. At 12-24 (RR 0.85, 95% CI 0.77-0.95; P = .002) and 24-36 months (RR 0.74, 95% CI 0.66-0.84; P < .001), ILDKTs had a lower risk than waitlist-only controls. These findings of ILDKTs having a higher readmission risk than compatible controls, but a lower readmission risk after the first year than waitlist-only controls should be considered in regulatory/payment schemas and planning clinical care.

Survival Benefit with Kidney Transplants from HLA-Incompatible Live Donors.

BACKGROUND: A report from a high-volume single center indicated a survival benefit of receiving a kidney transplant from an HLA-incompatible live donor as compared with remaining on the waiting list, whether or not a kidney from a deceased donor was received. The generalizability of that finding is unclear. METHODS: In a 22-center study, we estimated the survival benefit for 1025 recipients of kidney transplants from HLA-incompatible live donors who were matched with controls who remained on the waiting list or received a transplant from a deceased donor (waiting-list-or-transplant control group) and controls who remained on the waiting list but did not receive a transplant (waiting-list-only control group). We analyzed the data with and without patients from the highest-volume center in the study. RESULTS: Recipients of kidney transplants from incompatible live donors had a higher survival rate than either control group at 1 year (95.0%, vs. 94.0% for the waiting-list-or-transplant control group and 89.6% for the waiting-list-only control group), 3 years (91.7% vs. 83.6% and 72.7%, respectively), 5 years (86.0% vs. 74.4% and 59.2%), and 8 years (76.5% vs. 62.9% and 43.9%) (P<0.001 for all comparisons with the two control groups). The survival benefit was significant at 8 years across all levels of donor-specific antibody: 89.2% for recipients of kidney transplants from incompatible live donors who had a positive Luminex assay for anti-HLA antibody but a negative flow-cytometric cross-match versus 65.0% for the waiting-list-or-transplant control group and 47.1% for the waiting-list-only control group; 76.3% for recipients with a positive flow-cytometric cross-match but a negative cytotoxic cross-match versus 63.3% and 43.0% in the two control groups, respectively; and 71.0% for recipients with a positive cytotoxic cross-match versus 61.5% and 43.7%, respectively. The findings did not change when patients from the highest-volume center were excluded. CONCLUSIONS: This multicenter study validated single-center evidence that patients who received kidney transplants from HLA-incompatible live donors had a substantial survival benefit as compared with patients who did not undergo transplantation and those who waited for transplants from deceased donors. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases.).

Equivalent outcomes with primary and retransplantation in African-American deceased-donor renal allograft recipients.

BACKGROUND: Graft survival following renal retransplantation has been inferior to that following primary allografting, particularly in African Americans (AAs) receiving deceased-donor (DD) kidneys. METHODS: Among 166 AA DD renal allograft recipients transplanted from July 2001 through July 2007, we compared the outcomes of 26 (16%) receiving a second graft with those of 140 primary cases. All patients received either thymoglobulin (ATG) or an IL-2 receptor antagonist for induction, and were maintained on either tacrolimus or sirolimus + mycophenolate mofetil +/- prednisone. RESULTS: When compared with primary transplants, regrafts received kidneys from older donors, were younger, more sensitized, more likely to receive ATG and to be maintained on prednisone, received more doses of ATG, and were less likely diabetic. There was no difference between primary and retransplant groups in overall patient or graft survival; incidence of acute rejection, CMV infection, BK nephropathy, or new-onset diabetes mellitus; and serum creatinine at 1 year. CONCLUSION: AA renal allograft recipients can undergo a second DD transplant with intermediate-term outcomes comparable to that of a primary graft, despite the presence of multiple immunologic and non-immunologic high-risk factors, by extending the course of ATG induction and continuing prednisone therapy in the vast majority of cases.

Outcome predictors in African-American deceased-donor renal allograft recipients.

The relative importance of donor and recipient risk factors in predicting outcomes in African-American (AA) renal allograft recipients receiving contemporary immunosuppression, including early steroid withdrawal, has not been previously examined. We assessed the impact of 21 risk factors on five primary outcomes in 132 deceased-donor AA renal allograft recipients transplanted from July 2001 to August 2006 with follow-up 6-67 (mean 35 +/- 17) months by univariate and multivariate analysis. Thymoglobulin or basiliximab was given for induction, and mycophenolate mofetil with either tacrolimus or sirolimus (SRL) +/- prednisone for maintenance. Non-compliance accounted for 26% of graft loss (GL) and 19% of acute rejection (AR) episodes, and was more prevalent in patients who were HCV+ and those on prednisone. Delayed graft function remained a significant predictor of GL, but not via increased AR, and donor ethnicity emerged as an important predictor of patient death. De novo use of SRL resulted in increased AR, and only increased recipient age significantly predicted new-onset diabetes mellitus. Our preliminary results suggest the need for improvements in patient education, pre-transplant psychosocial assessment, and late post-transplant psychosocial support and can be utilized to help guide donor/recipient selection and tailor immunosuppressive management to optimize outcomes in this challenging group of patients.

Preliminary experience with renal transplantation in HIV+ recipients: low acute rejection and infection rates.

BACKGROUND: Only four centers have reported their results with renal transplantation in human immunodeficiency virus (HIV)+ recipients on highly active antiretroviral therapy, and acute rejection (AR) rates have consistently ranged from 43% to 67%. METHODS: We examined the outcomes of eight adult HIV+ primary renal allograft recipients with median 15 (range 8-47) months follow-up with multiple other high-risk factors, including African American ethnicity, hepatitis C virus (HCV) positivity, long waiting times, prior sensitization, paucity of live donors, and delayed graft function. Our immunosuppressive protocol consisted of an anti-interleukin-2 receptor antibody for induction, and mycophenolate mofetil, cyclosporin A, and prednisone for maintenance. Initial and 3- to 6-month cyclosporin A trough level targets were 250 to 300 and 225 to 275 ng/mL, respectively, and mycophenolate mofetil dose was adjusted according to 2 to 4 week surveillance and subsequent as needed mycophenolic acid predose concentrations during the first 6 months. RESULTS: Patient and graft survival were 100% and 88%, respectively, with an AR rate of 13% and excellent renal function. No patients developed new-onset diabetes, opportunistic or other serious infections, malignancy, or progression of hepatitis C virus-related liver disease. Excellent suppression of HIV replication with maintenance of CD4 counts was noted in all cases. CONCLUSIONS: Our findings suggest that HIV+ patients on highly active antiretroviral therapy can undergo successful renal transplantation with a low incidence of both AR and AIDS-associated and non-AIDS associated infections, despite associated risk factors for poorer outcome. Our encouraging but preliminary results with this protocol will need to be verified in larger numbers of HIV+ renal allograft recipients with longer follow-up.

Intermediate-term outcomes of hepatitis C-positive compared with hepatitis C-negative deceased-donor renal allograft recipients.

BACKGROUND: Prior studies have yielded conflicting results concerning the impact of HCV on renal transplant outcomes. METHODS: We examined outcomes in comparable groups of predominantly African American hepatitis C virus (HCV)-positive (n = 34) and HCV-negative (n = 111) kidney transplant patients receiving contemporary immunosuppression. RESULTS: There was no difference in patient survival or acute rejection, but new-onset diabetes (NODM) was increased and graft survival decreased in the HCV-positive group, with increased graft loss secondary to noncompliance and Type I MPGN. The incidence of NODM among patients undergoing early corticosteroid withdrawal was 11% in both groups, while among those on prednisone, it was 47% in HCV-positive versus 25% in HCV-negative recipients. CONCLUSIONS: Deceased-donor HCV-positive renal allograft recipients have equivalent patient but decreased graft survival. Noncompliance and Type I MPGN play a role in producing this negative effect on graft outcome. Steroids may be required for HCV to exert its diabetogenicity in kidney transplant patients.

Intermediate-term outcomes with early steroid withdrawal in African-American renal transplant recipients undergoing surveillance biopsy.

BACKGROUND: There is a paucity of data regarding the use of early corticosteroid withdrawal (ESW) in African-American renal allograft recipients, and very few reports with >or=1 year follow-up in all patients. METHODS: We examined the outcomes of 57 African-American renal allograft recipients with minimum follow-up 12 months who did not receive maintenance steroids after day 4 posttransplant. All patients received thymoglobulin induction, mycophenolate mofetil, and initial tacrolimus (n = 48) or sirolimus (n = 9). RESULTS: Patient and graft survival were 98% and 96% at 1 year, and 95% and 89% over the entire follow-up period (mean, 23 +/- 8 months). Incidence of acute rejection and cytomegalovirus infection were 18% and 7%, respectively, with mean serum creatinine 1.6 +/- 0.5 and 1.7 +/- 0.9 mg/dL at 6 and 12 months. Of patients with functioning grafts, 84% remained steroid free at 1 year, of which 11 (24%) were also calcineurin inhibitor free. Twenty-seven patients underwent surveillance biopsy at 1 month and 28 at 12 months, with 15 surveyed at both time points. There were significant increases in only 2 of the 6 1997 Banff chronic allograft nephropathy (CAN) category scores in this subgroup, with all mean values remaining <1 (mild in severity) at 1 year. Overall, from 82% to 96% of the 12-month scores were

Sirolimus exposure during the early post-transplant period reduces the risk of CMV infection relative to tacrolimus in renal allograft recipients.

INTRODUCTION: There are limited data regarding the role of individual maintenance immunosuppressive agents in the development of cytomegalovirus (CMV) infection. We examined the association between exposure to sirolimus (SRL) and risk of CMV infection after kidney transplantation when compared with tacrolimus (TCL). METHODS: This is a retrospective observational study of adult renal allograft recipients transplanted between 2001 and 2005 at our center. Patients received anti-lymphocyte antibody induction, and mycophenolate mofetil with either SRL or TCL +/- prednisone. D+/R- patients received valganciclovir 900 mg/d and CMV + patients 450 mg/d for three months. CMV infection was diagnosed with pp65 antigenemia testing prompted by clinical suspicion. RESULTS: A total of 14 Cases with CMV infection and 129 Controls were identified for primary analysis, and 11 D+/R- Cases and 19 D+/R- Controls for secondary analysis. The groups were comparable in both analyses, except for D+/R- serostatus in the primary analysis. All 14 Cases were on TCL for at least three months prior to diagnosis of CMV infection. In the primary analysis, zero Cases, but 30.2% and 34.9% of Controls (p = 0.009 and 0.004), and in secondary analysis, zero Cases, but 31.6% and 42.1% of Controls (p = 0.046 and 0.013), were on SRL at one and three months, respectively. In the primary analysis, zero Cases vs. 45 Controls (p = 0.004), and in secondary analysis, zero Cases vs. eight Controls (p = 0.013), were on SRL for at least three months early post-transplantation. CONCLUSION: These findings suggest that SRL as a component of a multidrug immunosuppressive regimen decreases the risk of CMV infection after kidney transplantation when compared with TCL.

Infectious complications after kidney transplantation: current epidemiology and associated risk factors.

BACKGROUND: The impact of newer immunosuppressive and antimicrobial prophylactic agents on the pattern of infectious complications following kidney transplantation has not been well studied. METHODS: This is an observational study in 127 adult recipients transplanted from 2001 to 2004. Patients received thymoglobulin (ATG) (50%) or basiliximab (50%) for induction and were maintained on mycophenolate mofetil, either tacrolimus (73%) or sirolimus (SRL) (27%), and prednisone (79%). Antimicrobial prophylaxis included perioperative cefazolin, trimethoprim/sulfamethaxazole for six months, valganciclovir for three months and nystatin for two months. Regression models were used to examine the association of various factors with infections. RESULTS: We observed 127 infections in 65 patients, consisting of urinary tract infection (UTI) (47%), viral infections (17%), pneumonia (8%) and surgical wound infections (7%). UTI was the most common infection in all post-transplant periods. Enterococcus spp. (33%) and Escherichia coli (21%) were the most prevalent uropathogens. Of six patients with cytomegalovirus infection, none had tissue-invasive disease. There were no cases of pneumocystis pneumonia or BK nephropathy. Six patients developed fungal infections. Two deaths due to disseminated Rhizopus and Candida albicans accounted for a 1.5% infection-related mortality. Retransplantation and ureteral stents were independently associated with UTI (OR=4.5 and 2.9, p=0.06 and 0.03, respectively), as were ATG and SRL with bacterial infections (OR=3.3 and 2.5, p=0.009 and 0.047, respectively). CONCLUSION: This study suggests that the use of newer immunosuppressive agents in recent years is associated with some changes in the epidemiology of post-transplant infections. Enterococci have become the predominant uropathogen. Invasive fungal infections, although rare, are often fatal.

Predictive value of human leucocyte antigen epitope matching using HLAMatchmaker for graft outcomes in a predominantly African-American renal transplant cohort.

The HLAMatchmaker program is based on the donor/recipient comparison of the polymorphic triplet amino-acid sequences of the antibody-accessible regions on the human leucocyte antigen (HLA) molecule. The previous reports on its predictive value for renal allograft outcomes are conflicting. We conducted a retrospective study in a predominantly African-American (AA) cohort (N = 101, 94% AA). HLA typing was performed by molecular methods and triplet matching using HLAMatchmaker. Study end points included graft survival and incidence of acute rejection. The relationship between the number of triplet mismatches (TMM) and the degree of HLA antigen MM was evaluated using Pearson's correlation coefficient. Logistic regression models were used to examine the association between triplet matching and the study end points. Kaplan-Meier and Cox proportional hazard models were used for graft survival analysis. The strongest relationship between the number of TMM and HLA antigen MM was observed for HLA-DQ (r = 0.88). The association between triplet matching at HLA-A, -B, -DR and -DRw HLA loci and the study end points was not statistically significant. However, after grouping, the unadjusted estimates of graft survival for those with more than 10 Class I TMM were significantly worse than the others (p = 0.03). Adjusting for the effect of donor source, recipient characteristics and the immunosuppressive regimen did not change this association (hazard ratio = 0.2, confidence interval = 0.04-1.1). We conclude that triplet matching using HLAMatchmaker can provide useful prognostic information in kidney transplantation and that more than 10 donor/recipient Class I HLA TMM is predictive of worse graft outcome.

Preliminary results with early corticosteroid withdrawal in African American renal allograft recipients.

BACKGROUND: There is a paucity of data regarding the use of steroid-avoidance immunosuppression (SAI) in African American (AA) renal allograft recipients, traditionally considered a high-risk subgroup of patients with higher reported rates of acute rejection and graft loss. METHODS: We compared the outcomes of 27 AA renal allograft recipients receiving SAI (SA group; mean follow-up period, 12 +/- 3 mo) with those of 20 patients receiving a steroid taper (ST group; 24 +/- 11 mo). In both groups, thymoglobulin was used for induction, and mycophenolate mofetil and tacrolimus were used for maintenance. Four doses of methylprednisolone were given on days 0 to 3. In the SA group no further steroids were given, whereas in the ST group a prednisone taper was continued thereafter. RESULTS: ST patients were more likely to have current panel reactive antibody titers greater than 10%, undergo retransplantation, and receive more doses of thymoglobulin. There were no significant differences between the SA and ST groups with regard to patient survival (96% vs 95%), graft survival (96% vs 90%), acute rejection (11% vs 14%), cytomegalovirus infection (7% vs 10%), posttransplant diabetes mellitus (11% vs 24%), or mean serum creatinine concentration at 6 months (1.6 vs 1.5 mg/dL), respectively, with a trend toward less percent weight gain in SA patients at 6 months (5% vs 11%, P = .06). CONCLUSIONS: SAI can produce excellent short-term results in AA kidney transplant patients when compared with a conventional ST protocol. Our results will need to be verified in larger numbers of patients with longer follow-up evaluation.

Cytomegalovirus prophylaxis with valganciclovir in African-American renal allograft recipients based on donor/recipient serostatus.

There is a paucity of data examining the efficacy of valganciclovir (VGC) for cytomegalovirus (CMV) prophylaxis in kidney transplant patients, particularly with regard to utilization of a risk-stratified dosing regimen. Eighty adult African-American (AA) renal allograft recipients transplanted from November 3, 2001 to May 28, 2003 and followed for 22 +/- 8 months received VGC once daily for 90 d post-transplant dosed according to donor/recipient (D/R) serostatus: high risk (D+/R-) received 900 mg (n = 12); moderate risk (D+/R+, D-/R+) received 450 mg (n = 60); and low risk (D-/R-) received no prophylaxis (n = 8). Thymoglobulin or basiliximab was used for induction, and mycophenolate mofetil, prednisone, and either tacrolimus or sirolimus for maintenance immunosuppression. Only six patients (7.5%) developed symptomatic CMV infection diagnosed by pp65 antigenemia, three in the high-risk (25%) and three in the moderate-risk (5%) group (p = 0.02). All patients were on tacrolimus for at least 3 months prior to diagnosis. There were no cases of tissue-invasive disease, resistance to treatment, or recurrence. D+/R- serostatus was the only significant independent predictor for CMV infection using multivariate analysis (odds ratio 10.5; p = 0.04). Thymoglobulin induction was not associated with CMV infection. None of 43 patients who were exposed to sirolimus for >30 d developed CMV infection, vs. six of 37 who were not (p = 0.006). We conclude that VGC dosed according to D/R serostatus provides safe and effective CMV prophylaxis in AA renal allograft recipients.

Induction therapy with basiliximab versus Thymoglobulin in African-American kidney transplant recipients.

BACKGROUND: It has been suggested that the use of antilymphocyte induction therapy in African-American (AA) renal transplant recipients reduces the risk of acute rejection (AR) and improves graft survival. It is not clear whether the efficacy of basiliximab (BSX) is different from that of Thymoglobulin (ATG) in this regard. METHODS: We retrospectively assessed the effect of induction therapy with BSX versus ATG in 88 AA renal allograft recipients receiving transplants at our center between July 2001 and June 2003 and followed for 19+/-7 months. All patients were maintained on mycophenolate mofetil, prednisone, and either tacrolimus or sirolimus. Study endpoints included patient and graft survival, graft function, and incidence of AR and cytomegalovirus infection. Regression models were used to evaluate the independent effect of each induction agent on these endpoints. RESULTS: Thirty-six patients received ATG, and 52 received BSX. The groups were comparable with regard to donor race and age, and recipient sex, body mass index, human leukocyte antigen (HLA) matching, and hepatitis C virus serostatus. The ATG group was younger, more likely to receive retransplant, had longer duration of end-stage renal disease and higher panel reactive antibody, and was less likely to receive live-donor organs. However, after adjusting for all these variables, graft outcomes, as well as renal function, were comparable between the two induction groups. We found that the degree of HLA mismatch, delayed graft function, and AR were the only significant predictors of graft loss. CONCLUSION: The results of our study suggest that the choice of induction agent may not have a major impact on graft outcomes in AA renal-allograft recipients.

West Nile virus encephalitis: an emerging disease in renal transplant recipients.

West Nile virus (WNV) has emerged as an important cause of several outbreaks of febrile illness and encephalitis in North America over the past few years. The most common manifestation in symptomatic patients is a transient febrile illness. Neuroinvasive disease, that can be fatal, occurs most often in elderly and immunocompromised hosts. The role of this virus as a cause of meninoencephalitis in organ transplant recipients is becoming better recognized. We describe herein the clinical course of two renal allograft recipients who developed WNV encephalitis. One patient developed status epilepticus and eventually died, while the other had a full recovery. In both cases, the diagnosis was confirmed by detection of WNV-specific IgM in CSF or serum, with a delayed antibody response in one patient. This viral infection should be considered in all renal transplant recipients who present with a febrile illness associated with neurological symptoms.

Sirolimus-induced angioedema.

Sirolimus (SRL) is a macrolide immunosuppressant that has gained widespread use in organ transplantation. Its full spectrum of side-effects is yet to be defined. We describe herein three cases of SRL-induced angioedema (AE) in African-American (AA) primary renal allograft recipients who received SRL in combination with mycophenolate mofetil and steroids. In two cases, AE manifested after SRL was restarted after a period of discontinuation. The third case presented upon initial exposure to the drug. None of the patients was receiving any drug that has been previously associated with AE. Complete resolution occurred only after SRL was withdrawn. AE has not recurred in any of the patients during a follow-up period of up to 21 months. We conclude that AE is a previously unrecognized adverse event associated with SRL use. Close monitoring for this side-effect, especially in AA patients, is warranted.