Anti-human Leukocyte Antigen Antibodies Research Articles

Clinical and investigational use of proteasome inhibitors for transplant rejection

Introduction:The presence of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSA) in patients experiencing acute cellular rejection and antibody-mediated rejection (AMR) is associated with poor renal allograft survival in kidney transplant recipients. Traditional therapies for AMR provide variable results, and do not deplete the cellular source of antibody production, that is, the plasma cell.Areas covered:Physiologic effects of proteasome inhibitors (PIs) are reviewed in the context of recent clinical reports of PI therapy in solid organ transplantation for AMR and desensitization.Expert opinion:PI-based therapy is a novel approach for treating AMR that is being employed with increasing frequency in transplantation. Initial reports of PI-based regimens for treating AMR have demonstrated the ability of bortezomib to significantly reduce DSA levels and improve histology and allograft function. Use of PI agents have recently been evaluated in a large multicenter collaborative consisting of over 100 solid organ transplant recipients treated with a common PI-based regimen. Increasing experience with PI-based regimens for AMR have indicated that PI therapy (similar to other AMR therapies) provides excellent results in early AMR, with late AMR demonstrating a greater degree of therapeutic resistance. A substantial number of strategies exist for enhancement of therapeutic results with PI therapy for AMR.

Effect of sensitization in US heart transplant recipients bridged with a ventricular assist device: Update in a modern cohort

Preformed anti-human leukocyte antigen antibodies have been associated with prolonged wait times and increased mortality in orthotopic heart transplantation. We used United Network for Organ Sharing data to examine panel reactive antibody titers in patients bridged to transplant with left ventricular assist devices. This was a retrospective review of the United Network for Organ Sharing dataset for all patients bridged to orthotopic heart transplantation with a HeartMate II or HeartMate XVE (Thoratec Corp, Pleasanton, Calif) from January 2004 to December 2009. Patients were primarily stratified by device type and secondarily grouped for comparisons by high (>25%) versus low (0%) panel reactive antibody activity (class I and II). Outcomes included survival (30-day and 1-year), treated rejection in the year after orthotopic heart transplantation, and primary graft dysfunction. Cox proportional hazards regression examined 30-day and 1-year survival. A total of 871 patients (56.1%) received the HeartMate II device, and 673 patients (43.9%) received the HeartMate XVE device. Patients with high panel reactive antibody had longer duration on the wait list (205 days [interquartile range, 81-344] vs 124 days [interquartile range, 51-270], P = .01). High panel reactive antibody class II was more common in patients with the HeartMate XVE device (51/547 [9.3%] vs 42/777 [5.4%], P < .001). When the entire cohort was examined together, there was no 30-day or 1-year survival difference based on panel reactive antibody activity. Device type did not affect post-orthotopic heart transplantation survival, and panel reactive antibody activity was not associated with worse mortality in Cox regression. Although panel reactive antibody activity did not affect rejection in the year after orthotopic heart transplantation for either device type, high panel reactive antibody class II was associated with higher rates of primary graft dysfunction for both devices (P < .05). This is the largest modern study to examine the impact of detailed panel reactive antibody information in patients bridged to transplant. High panel reactive antibody levels do not affect drug-treated rejection episodes in the first year post-orthotopic heart transplantation; however, there is an associated higher rate of primary graft dysfunction, regardless of device type. Highly sensitized patients bridged to transplant experience excellent survival outcomes after orthotopic heart transplantation.

Clinical relevance of HLA donor-specific antibodies detected by single antigen assay in kidney transplantation

Clinical relevance of donor-specific antibodies (DSAs) detected by a single antigen Luminex virtual crossmatch in pre-transplant serum samples from patients with a negative cytotoxicity-dependent complement crossmatch is controversial. The aim of this study was to analyse the influence of a pre-transplant positive virtual crossmatch in the outcome of kidney transplantation. A total of 892 patients who received a graft from deceased donors after a negative cytotoxicity crossmatch were included. Presence of anti-human leucocyte antigen (HLA) antibodies was investigated using a Luminex screening assay and anti-HLA specificities were assigned performing a Luminex single antigen assay. Graft survival was significantly worse among patients with anti-HLA DSA compared to both patients with anti-HLA with no DSA (P = 0.001) and patients without HLA antibodies (P < 0.001) using a log-rank test. No graft survival differences between anti-HLA with no DSA and no HLA antibodies patient groups were observed (P = 0.595). Influence of both anti-Class I and anti-Class II DSA was detected (P < 0.0001 in both cases). When the fluorescence values were stratified in four groups, no significant differences in graft survival were observed among the groups with fluorescence levels >1500 (global P > 0.05). The presence of preformed HLA DSA in transplanted patients with a negative cytotoxicity crossmatch is associated with a lower allograft survival. The detection of anti-HLA with no DSA has no influence in the graft outcome. Finally, there were no demonstrable effects of mean fluorescence intensity (MFI) values >1500 on graft survival.

Antibody Testing Strategies for Deceased Donor Kidney Transplantation After Immunomodulatory Therapy

Immunomodulatory protocols including intravenous immunoglobulin/rituximab (IVIG/R) are employed to decrease anti-human leukocyte antigen (HLA) antibody levels for patients broadly sensitized to HLA and increase chances for transplantation with a compatible deceased donor (DD). The aim of our study was to identify the optimal antibody levels allowing for selection of compatible DDs for these sensitized patients. From January 2006 to December 2009, 108 patients broadly sensitized to HLA who had reached the top of the DD waitlist were treated with IVIG/R. Antibody levels were monitored monthly by Luminex-based single-antigen bead assay. The antigens identified to produce positive complement-dependent cytotoxicity crossmatches (XMs; >200,000 standard fluorescence intensity [SFI]/10,000 median fluorescence intensity [MFI]) were determined to be unacceptable and entered into the United Network for Organ Sharing database generating the calculated panel reactive antibody (CPRA). The mean CPRA (mCPRA) for this group was more than 80. DDs were selected based on T-cell flow XMs (FXMs) less than 250 MCS and B-cell FXMs less than 300 mean channel shifts (MCS). Monthly Luminex-based single-antigen assays showed that the IVIG/R therapy decreased antibody levels for a period of 30 to 120 days. Of the 108 patients treated, 80 (74%) were transplanted and 28 (26%) were not (mCPRA 96 ± 11). Forty-two (53%) patients were transplanted with a positive FXM; 28 (35%) patients (mCPRA 84 ± 25) were transplanted with a negative FXM; and 10 patients (12%; mCPRA 90 ± 19) received zero HLA ABDR mismatched grafts. After therapy, careful selection of acceptable DD involves the antibody profiling strength and XM results. These approaches provide patients broadly sensitized to HLA with an opportunity for compatible DD transplantation.

A case of progressive thrombotic microangiopathy after ABO‐incompatible renal transplantation

A 21-yr-old man of blood type O receiving hemodialysis for IgA nephropathy underwent living-related ABO-incompatible (ABOI) renal transplantation from his mother, whose blood type is A. He was negative for flow cross-match, anti-human leukocyte antigen (HLA) antibody, and anti-MICA antibody. Pre-treatment anti-A IgG titer was 1:256. Desensitization consisted of tacrolimus, mycophenolate mofetil, methylprednisolone, rituximab, and plasmapheresis. He developed acute antibody rejection at day 2 post-transplant, which was successfully treated. After renal artery reconstruction surgery at day 91 for renovascular hypertension caused by renal artery stricture, the patient suffered from acute prostatitis, which subsequently induced type III acute antibody-mediated rejection. Even after recovery from the rejection after temporary hemodialysis, graft function progressively deteriorated and consecutive allograft biopsy showed progressive thrombotic microangiopathy (TMA) without any evidence of donor-specific antibody other than anti-A antibody. The tacrolimus dose was kept low for fear of tacrolimus-induced TMA. Despite these efforts, the patient resumed hemodialysis six months' post-transplant.

A case of transplant glomerulopathy early after kidney transplantation

Transplant glomerulopathy (TG) has commonly been described as a late manifestation of allograft injury, occurring years after renal transplantation. We describe herein a patient who developed TG early (49 days) after kidney transplantation (KTx). A 44-yr-old woman received a second living-related KTx from her younger brother in October 2009. Pre-transplant donor-specific anti-human leukocyte antigen antibodies (DSA) were positive for both class I and class II. During the renal transplant operation, she suffered from hyperacute antibody-mediated rejection (AMR) and intravenous immune globulin therapy was immediately performed. Once hyperacute AMR was resolved, accelerated acute AMR occurred on the first post-transplant day (PTD). The renal allograft biopsy performed on PTD 19 diagnosed acute AMR type II. The renal allograft biopsy performed on PTD 49 showed focal lesions of double contours of glomerular basement membranes in some glomeruli. Interstitial fibrosis showed a strong, diffuse staining of C4d in peritubular capillaries (PTCs). The DSA examined on PTD 39 were still positive for both class I and class II. From these histopathological findings of TG, C4d deposition in PTC and presence of circulating DSA, we diagnosed this case to have c-AMR. TG might be recognized in early after KTx.

Immunologic Considerations in Heart Transplantation for Congenital Heart Disease

Children and adults with congenital heart disease (CHD) can require interventions that result in immunologic alterations that are different than those seen in patients with cardiomyopathies. Patients with CHD can be exposed to heart surgeries, blood products, valved and non-valved allograft tissue, and mechanical circulatory support, all of which can alter the immunologic status of these patients. This change in immunologic status is most commonly manifested as the development of anti-human leukocyte antigen (HLA) antibodies. This review will delineate a) the causes of anti-HLA anti-body production (often referred to as allosensitization); b) preventive strategies for anti-HLA antibody production before transplantation; c) treatment strategies for those patients who develop anti-HLA antibodies before transplantation; d) consequences of HLA allosensitization after transplantation; and e) treatment of HLA allosensitization and antibody-mediated rejection after transplantation.

A Signature of Maternal Anti-Fetal Rejection in Spontaneous Preterm Birth: Chronic Chorioamnionitis, Anti-Human Leukocyte Antigen Antibodies, and C4d

BackgroundChronic chorioamnionitis is found in more than one-third of spontaneous preterm births. Chronic chorioamnionitis and villitis of unknown etiology represent maternal anti-fetal cellular rejection. Antibody-mediated rejection is another type of transplantation rejection. We investigated whether there was evidence for antibody-mediated rejection against the fetus in spontaneous preterm birth.Methods and FindingsThis cross-sectional study included women with (1) normal pregnancy and term delivery (n = 140) and (2) spontaneous preterm delivery (n = 140). We analyzed maternal and fetal sera for panel-reactive anti-HLA class I and class II antibodies, and determined C4d deposition on umbilical vein endothelium by immunohistochemistry. Maternal anti-HLA class I seropositivity in spontaneous preterm births was higher than in normal term births (48.6% vs. 32.1%, p = 0.005). Chronic chorioamnionitis was associated with a higher maternal anti-HLA class I seropositivity (p<0.01), significant in preterm and term birth. Villitis of unknown etiology was associated with increased maternal and fetal anti-HLA class I and II seropositivity (p<0.05, for each). Fetal anti-HLA seropositivity was closely related to maternal anti-HLA seropositivity in both groups (p<0.01, for each). C4d deposition on umbilical vein endothelium was more frequent in preterm labor than term labor (77.1% vs. 11.4%, p<0.001). Logistic regression analysis revealed that chronic chorioamnionitis (OR = 6.10, 95% CI 1.29–28.83), maternal anti-HLA class I seropositivity (OR = 5.90, 95% CI 1.60–21.83), and C4d deposition on umbilical vein endothelium (OR = 36.19, 95% CI 11.42–114.66) were associated with preterm labor and delivery.ConclusionsA major subset of spontaneous preterm births has a signature of maternal anti-fetal cellular and antibody-mediated rejections with links to fetal graft-versus-host disease and alloimmune reactions.

Protective Immunity Remains Intact After Antibody Removal by Means of Proteasome Inhibition

Proteasome inhibition abrogates donor-specific anti-human leukocyte antigen (HLA) antibody (DSA) in patients posttransplant. However, its effects on protective humoral immunity to vaccine antigens remain unknown. Herein, we report on bortezomib's safety regarding protective immunity in patients who have experienced HLA antibody reduction/removal. Thirteen living donor renal transplant patients were treated with bortezomib one to two cycles (1.3 mg/m² × 4 doses) and plasmapheresis in 2008 to remove HLA antibodies posttransplant. Serial measurements of HLA antibody were conducted weekly before, during, and after treatment by means of single antigen bead on Luminex (One Lambda Inc., Canoga Park, CA). Measles and tetanus toxoid IgGs were measured quantitatively by using ELISA (American Research Products Inc., Belmont, MA). All patients treated with bortezomib/plasmapheresis resulted in a primary DSA reduction of more than 50%. In 10 of 13 patients, complete DSA removal (to below 1000 mean fluorescent intensity) occurred. At 1 year posttreatment, antibody intensity remains significantly depressed in the group as a whole. Despite the significant effect on antibody production, tetanus toxoid and measles IgG levels remained unchanged and above the level of protection at 1 year posttreatment. These data indicate that proteasome inhibitors plus plasmapheresis results in prolonged reduction of HLA antibodies while leaving protective immunity intact.

Desensitization and Heart Transplantation of a Patient With High Levels of Donor-Reactive Anti-Human Leukocyte Antigen Antibodies

To prepare a highly immunized recipient for heart transplantation, reduction of high levels of cytotoxic antibodies against human leukocyte antigen (HLA) was deemed essential to prevent antibody-mediated graft failure. Antibodies were analyzed by lymphocytotoxic and solid-phase assays. The pretransplant desensitization treatment protocol included daily tacrolimus and mycophenolate mofetil, weekly protein-A immunoadsorption (IA), intravenous immunoglobulin, and daclizumab. Posttransplant treatment consisted of tacrolimus, mycophenolate mofetil, prednisolone, IA, and daclizumab. During pretransplant desensitization, each of the weekly immunoadsorption treatments reduced anti-HLA antibody levels by 50% to 70%, but they returned to the pretreatment level within 1 week as measured by flow cytometry. Cytotoxic antibodies remained reduced. After perioperative immunoadsorption, the donor-reactive antibodies (DRAs) were reduced to low levels. The patient underwent successful heart transplantation after 6 weeks on a waiting list. During the first week posttransplant, DRAs remained low. However, after the first week, anti-HLA DRAs reappeared and increased slightly over a 3-week period and then decreased slowly. Cytotoxic crossmatches were negative before and 3 week after transplantation. No clinical rejection was encountered. The patient was doing well 3 years after transplantation, and yearly clinical cardiac investigations were all normal. Three hyperimmunized patients have now undergone successful heart transplantation at our center using this desensitization protocol. IA in combination with pretransplant immunosuppressive drug treatment temporarily reduces antibody levels. The therapeutic levels of drug treatment at the time of transplantation may be of crucial importance. The treatment protocol resulted in freedom from rejection and other clinical adverse events.

Transfusion-Related Acute Lung Injury, an Evolving Syndrome: The Road of Discovery, With Emphasis on the Role of the Mayo Clinic

Transfusion-related acute lung injury (TRALI) is characterized by acute hypoxemia and noncardiogenic pulmonary edema. At the very least, descriptions of cases consistent with TRALI date back to the early 1950s. Early articles from the 1950s and 1960s documented transfusion-associated pulmonary edema without evidence of volume overload. Explanations for this phenomenon included hypersensitivity and transfused leukoagglutinins. Descriptions from the 1970s also implicated transfused antileukocyte antibodies and noted that blood products containing such antibodies often came from multiparous female donors. Cases implicating recipient anti-human leukocyte antigen antibody reacting with transfused donor leukocytes and donor antibodies reacting with another donor's leukocytes were also described. The 1980s marked the emergence of the Mayo Clinic as a leading contributor to the understanding of TRALI. The descriptions of the syndrome that was named "TRALI" by Mayo Clinic investigators were the most extensive and complete to date and are presented in detail. The Mayo Clinic has remained in the forefront of TRALI investigation, particularly as it pertains to the critically ill, and recent studies from this center are also presented in detail. The common thread connecting the Mayo Clinic's descriptions in the 1980s to the more contemporary studies is Dr S. Breanndan Moore. Dr Moore passed away recently, but his crucial work in the area of TRALI lives on.

Renal thrombotic microangiopathy associated with chronic humoral graft versus host disease after hematopoietic stem cell transplantation

Thrombotic microangiopathy (TMA) is a known complication of hematopoietic stem cell transplantation (HSCT). The pathogenesis of TMA is controversial but considered to involve various factors such as total body irradiation, use of calcineurin inhibitors for prophylaxis against graft versus host disease (GVHD), viral infection, and GVHD. Herein we describe a case with renal TMA after HSCT, which was probably associated with antibody-mediated endothelial cell injury from chronic GVHD (termed here 'chronic humoral GVHD'). A 49-year-old man presented two years after HSCT with renal dysfunction and proteinuria but without the clinical features of TMA. Histopathological examination of renal biopsy showed chronic glomerular endothelial cell injury with double contour of the glomerular basement membrane, microthrombi and the deposition of complement split product C4d along the glomerular capillaries. Renal tubulitis and peritubular capillaritis were also noted with a multilayered basement membrane and patchy C4d deposition on peritubular capillaries. These findings resemble those of chronic antibody-mediated rejection after kidney transplantation. Furthermore, C4d deposition suggests complement activation. Although circulating anti-blood type and anti-human leukocyte antigen antibodies were not detected, the renal TMA in this case was probably associated with chronic humoral GVHD.

Panel reactive HLA antibodies, soluble CD30 levels, and acute rejection six months following renal transplant

Specific anti-human leukocyte antigen antibodies (HLA) in the post-transplant period may be present with acute rejection episodes (ARE), and high soluble CD30 (sCD30) serum levels may be a risk factor for ARE and graft loss. HLA cross-matching, panel reactive antibodies (PRA), and sCD30 levels were determined prior to transplantation in 72 patients. Soluble CD30 levels and PRA were re-assessed at day 7, 14, 21, and 28, and monthly up to the sixth. Twenty-four subjects had a positive PRA and 17 experienced ARE. Nine of 17 ARE subjects demonstrated positive PRA and 16 had HLA mismatches. Positive PRA was more frequent in ARE subjects (p = 0.03). Eight subjects with ARE had donor-specific antibodies (DSA) in serum samples pre-transplantation, two subjects developed DSA. Three subjects without ARE had positive PRA only in post-transplantation samples. Soluble CD30 levels were higher in pre-transplant samples and ARE subjects than non-ARE subjects (p = 0.03). Post-transplant sCD30 levels were elevated in subjects who experienced rejection and were significantly higher at seven d (p = 0.0004) and six months (p = 0.03). Higher sCD30 levels following transplant were associated with ARE. Elevated sCD30 levels may represent a risk factor for acute rejection.

Determinants of Long-Term Graft Outcome in Transplant Glomerulopathy

Transplant glomerulopathy (TG) is a renal allograft disease defined by glomerular basement membrane duplication with peritubular capillary basement membrane multilayering (PTCML), and associated with anti-human leukocyte antigen antibodies and C4d. Outcome in TG is poor but variable, and prognostic factors, particularly those affecting long-term outcome, are not well known. We investigated several potentially prognostic clinical and pathologic factors in TG and evaluated estimated glomerular filtration rate (eGFR) slopes to assess graft function and early decline. We examined all cases of TG from 2001 to 2005 with at least 4-year follow-up after biopsy, excluding those with a second confounding diagnosis. Among 36 cases of pure TG, mean graft age at biopsy was 8.8±6 years. C4d stain was positive in 11 (33%) cases. Clinical characteristics at biopsy were not different based on C4d. C4d was associated with greater PTCML (P=0.03), peritubular capillaritis (P=0.04), and glomerulitis (P=0.03). Death-censored graft survival was significantly associated with interstitial fibrosis (P=0.001), PTCML (P=0.001), and arteriolar hyalinosis (P=0.007), and it showed a trend with proteinuria (P=0.07) and C4d positivity (P=0.08). C4d-positive cases also showed a trend toward rapid graft loss. Analysis of eGFR slopes showed a pattern of preserved, slightly negative slope from transplant until approximately 1 year before biopsy, at which point the slope became significantly more negative (P<0.001). Interstitial fibrosis, PTCML, and arteriolar hyalinosis were significant predictors of graft survival in TG. C4d positivity was associated with a more rapid rate of function decline. eGFR slope data showed significant deterioration in graft function well before the diagnostic biopsy.

On solid-phase antibody assays

There is considerable evidence that pre-operative and post-operative anti-human leukocyte antigen (anti-HLA) antibodies are deleterious in thoracic transplantation. While debate continues in heart and lung transplantation on the role of and the diagnosis and treatment of antibody-mediated rejection (AMR), central to the discussion is our ability to detect anti-HLA antibodies. This perspective outlines the concerns elicited by new technology for detection of anti-HLA antibodies using solid-phase assays, and highlights the need for functional assays to further understand the clinical significance of these antibodies.

Alloimmunity and autoimmunity in chronic rejection

Recent studies demonstrate an increasing role for alloimmune responses in the disruption of self-tolerance leading to immune responses to self-antigens that play a role in the immunopathogenesis of chronic rejection following solid organ transplantation. This review summarizes recent studies and implications for the alloimmune-response-induced de-novo development of autoimmune responses following solid organ transplantations. Immediately following organ transplantation, several factors lead to enduring an inflammatory milieu. Studies from our laboratory and others have demonstrated that development of antihuman leukocyte antigen antibodies precedes the development of chronic rejection. Using an in-vivo murine model, we have demonstrated that administration of anti-major histocompatibility complex (MHC) class I directly into the native lungs leads to chronic rejection pathology. Further, the in-vitro ligation of epithelial cell surface MHC class I molecules by specific anti-MHC can lead to cell activation and production of fibrinogenic growth factors. On the basis of these findings, we hypothesized that alloimmune responses can lead to autoimmunity, thus playing an important role in chronic rejection. Characterization of both the temporal occurrence and functional significance of antibodies to self-antigens may provide insight into the pathogenesis of chronic rejection and these antibodies can serve as clinically useful biomarkers.

Donor-Specific Antibody Levels and Three Generations of Crossmatches to Predict Antibody-Mediated Rejection in Kidney Transplantation

This study evaluated the prognostic impact of pretransplant donor-specific anti-human leukocyte antigen antibodies (DSA) detected by single-antigen beads and compared the three generations of crossmatch (XM) tests in kidney transplantation. Thirty-seven T-cell complement-dependent cytotoxicity crossmatch (CXM) negative living donor kidney recipients with a retrospectively positive antihuman leukocyte antigen antibody screening assay were included. A single-antigen bead test, a flow cytometry XM, and a Luminex XM (LXM) were retrospectively performed, and the results were correlated with the occurrence of antibody-mediated rejections (AMRs) and graft function. We found that (1) pretransplant DSA against class I (DSA-I), but not against class II, are predictive for AMR, resulting in a sensitivity of 75% and a specificity of 90% at a level of 900 mean fluorescence intensity (MFI); (2) with increasing strength of DSA-I, the sensitivity for AMR is decreasing to 50% and the specificity is increasing to 100% at 5200 MFI; (3) the LXM for class I, but not for class II, provides a higher accuracy than the flow cytometry XM and the B-cell CXM. The specificity of all XMs is increased greatly in combination with DSA-I values more than or equal to 900 MFI. In sensitized recipients, the best prediction of AMR and consecutively reduced graft function is delivered by DSA-I alone at high strength or by DSA-I at low strength in combination with the LXM or CXM.

Evaluation of Low-Dose Rituximab Induction Therapy in Living Related Kidney Transplantation

Rrituximab has been used for desensitization of anti-blood type antibody and anti-human leukocyte antigen (HLA) antibody as an induction immunosuppressant in our hospital. After having used rituximab for more than 2 years, we performed a retrospective study to clarify the effectiveness and safety of rituximab. We performed 144 kidney transplants between January 2005 and December 2007 at our hospital. Low-dose rituximab was administered to 78 of these transplant recipients as an induction immunosuppressant. A comparison of viral infection, leucopenia, and rejection incidence between patients administered (Rit group) and not administered (Non-Rit group) rituximab before kidney transplantation was performed. A comparison of Rit group and Non-Rit group revealed no significant difference in the incidence of cytomegalovirus infections (Rit: 26%, Non-Rit: 29%; P=1.00), BK virus infections (Rit: 2.6%, Non-Rit: 0%; P=0.53), or leukopenia (Rit:23%, Non-Rit: 14%; P=0.25) between the two groups of patients. The incidence of acute antibody-mediated rejection was also not significantly different between the two groups (Rit: 6.8%, Non-Rit: 8.3%; P=0.75). On the other hand, the incidence of acute T-cell-mediated rejection was significantly lower in the Rit group (Rit: 8.2%, Non-Rit: 23.3%; P<0.05). Anti-HLA antibodies belonging to HLA class 1 and class 2 were depleted by 70% and 83%, respectively, for more than 2 years after rituximab administration. We could confirm the effectiveness and safety of rituximab more than 2-year follow-up period.

Anti-human leukocyte antigen antibodies and preemptive antibody-directed therapy after lung transplantation

Because the development of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSA) after lung transplantation has been associated with acute and chronic rejection, we implemented a clinical protocol to screen all transplant recipients for DSA and preemptively treat those who developed DSA with rituximab and intravenous immune globulin (IVIG), or IVIG alone. We conducted a prospective observational study of this protocol and used the LABScreen Single Antigen assay to detect DSA after transplantation. We compared the incidence of acute rejection, lymphocytic bronchiolitis, and bronchiolitis obliterans syndrome (BOS) between those who developed DSA and those who did not using Cox proportional hazards models. We used the Kaplan-Meier method to compare freedom from BOS and survival between those who had persistent DSA and those who had successful depletion of DSA. Among 116 recipients screened, DSA developed in 65 during the study period. Those who developed DSA and received antibody-directed therapy had a similar incidence of acute rejection, lymphocytic bronchiolitis, and BOS as those who did not develop DSA. Furthermore, recipients who had successful depletion of DSA had greater freedom from BOS and better survival than those who had persistent DSA. Finally, those treated for DSA had a similar incidence of infectious complications as those who did not develop DSA. The development of DSA is surprisingly common after lung transplantation. Antibody-directed therapy may reduce the risk of rejection associated with DSA, but a randomized controlled trial is necessary to critically evaluate the efficacy of this treatment protocol.

Significance and Implications of Capillaritis During Acute Rejection of Kidney Allografts

BACKGROUND.: Anti-human leukocyte antigen antibodies (a-HLA) cause graft injury identified by C4d in peritubular capillaries. We investigated whether a-HLA relate to episodes of C4d negative acute rejection (AR). METHODS.: We analyzed 878 kidney recipients transplanted from January 2000 to December 2006. Pretransplant, 36% of these crossmatch negative recipients had a-HLA measured by solid phase assays. RESULTS.: AR occurred in 154 patients (18%) and 11 of them (9.4%) were C4d+. Forty-six percent of ARs were diagnosed by protocol biopsy. The risk of C4d-AR was increased in patients with a-HLA class I with donor specificity (DSA-I) (hazard ratio=1.519; confidence interval, 1.02-2.26; P=0.039). DSA-II were not associated with an increased risk of C4d-AR. The relationship between DSA-I and C4d-AR was independent of recipient age, BK nephropathy, and HLA mismatches. Compared with DSA-, in DSA+ recipients C4d-AR were most often histologically "borderline." DSA+ was associated with capillaritis in the biopsy (glomerulitis, 6.1% vs. 32%, P=0.003; peritubular capillaritis: 13% vs. 40%, P=0.0009). Compared with no AR, C4d-AR with capillaritis was associated with reduced graft survival (hazard ratio=4.164; confidence interval, 1.763-9.832; P=0.001), independent of other variables. This association was observed even in the cases of borderline AR. CONCLUSIONS.: DSA-I increases the risk of C4d-AR. The presence of DSA-I or II is associated with capillaritis during AR. Capillaritis is associated with reduced graft survival.