Impact of allele-specific anti-human leukocyte antigen class I antibodies on organ allocation.

Technological advances in the field of histocompatibility have allowed us to define anti-human leukocyte antigen (HLA) antibody specificity at the allelic level. However, how allele-specific antibodies affect organ allocation is poorly studied. We examined allelic specificities of class I HLA antibodies in 6726 consecutive serum samples from 2953 transplant candidates and evaluated their impact on the corresponding crossmatch and organ allocation. Out of 17 class I HLA antigens represented by >1 allele in the LABScreen single antigen bead assay, 12 had potential allele-specific reactivity. Taking advantage of our unbiased cohort of deceased donor-candidate testing (123,135 complement-dependent cytotoxicity crossmatches between 2014 and 2017), we estimated that the presence of allele-specific antibody detected using a single antigen bead assay (median fluorescence intensity, >3000) against only the rare allele was a poor predictor of a positive complement-dependent cytotoxicity crossmatch, with a positive predictive value of 0% to 7%, compared with 52.5% in allele-concordant class I HLA antibodies against A or B locus antigens. Further, we confirmed allele-specific reactivity using flow crossmatch in 3 scenarios: A11:01/A11:02, A68:01/A68:02, and B44:02/B44:03. Our results suggest that allele-specific antibodies may unnecessarily exclude transplant candidates (up to 10%) from organ offers by overcalling unacceptable antigens; incorporation of selective reactivity pattern in allocation may promote precision matching and more equitable allocation.

ABO Genotyping finds more A2 to B kidney transplant opportunities than lectin-based subtyping.

ABO compatibility is important for kidney transplantation, with longer waitlist times for blood group B kidney transplant candidates. However, kidneys from non-A1 (eg, A2) subtype donors, which express less A antigen, can be safely transplanted into group B recipients. ABO subtyping is routinely performed using anti-A1 lectin, but DNA-based genotyping is also possible. Here, we compare lectin and genotyping testing. Lectin and genotype subtyping was performed on 554 group A deceased donor samples at 2 transplant laboratories. The findings were supported by 2 additional data sets of 210 group A living kidney donors and 124 samples with unclear lectin testing sent to a reference laboratory. In deceased donors, genotyping found 65% more A2 donors than lectin testing, most with weak lectin reactivity, a finding supported in living donors and samples sent for reference testing. DNA sequencing and flow cytometry showed that the discordances were because of several factors, including transfusion, small variability in A antigen levels, and rare ABO∗A2.06 and ABO∗A2.16 sequences. Although lectin testing is the current standard for transplantation subtyping, genotyping is accurate and could increase A2 kidney transplant opportunities for group B candidates, a difference that should reduce group B wait times and improve transplant equity.

Peripheral host T cells survive hematopoietic stem cell transplantation and promote graft-versus-host disease.

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality in hematopoietic stem cell transplantation (HSCT). Donor T cells are key mediators in pathogenesis, but a contribution from host T cells has not been explored, as conditioning regimens are believed to deplete host T cells. To evaluate a potential role for host T cells in GVHD, the origin of skin and blood T cells was assessed prospectively in patients after HSCT in the absence of GVHD. While blood contained primarily donor-derived T cells, most T cells in the skin were host derived. We next examined patient skin, colon, and blood during acute GVHD. Host T cells were present in all skin and colon acute GVHD specimens studied, yet were largely absent in blood. We observed acute skin GVHD in the presence of 100% host T cells. Analysis demonstrated that a subset of host T cells in peripheral tissues were proliferating (Ki67+) and producing the proinflammatory cytokines IFN-γ and IL-17 in situ. Comparatively, the majority of antigen-presenting cells (APCs) in tissue in acute GVHD were donor derived, and donor-derived APCs were observed directly adjacent to host T cells. A humanized mouse model demonstrated that host skin-resident T cells could be activated by donor monocytes to generate a GVHD-like dermatitis. Thus, host tissue-resident T cells may play a previously unappreciated pathogenic role in acute GVHD.

Development of a Calculated Panel Reactive Antibody Web Service with Local Frequencies for Platelet Transfusion Refractoriness Risk Stratification.

BACKGROUND: Calculated panel reactive antibody (cPRA) scoring is used to assess whether platelet refractoriness is mediated by human leukocyte antigen (HLA) antibodies in the recipient. cPRA testing uses a national sample of US kidney donors to estimate the population frequency of HLA antigens, which may be different than HLA frequencies within local platelet inventories. We aimed to determine the impact on patient cPRA scores of using HLA frequencies derived from typing local platelet donations rather than national HLA frequencies. METHODS: We built an open-source web service to calculate cPRA scores based on national frequencies or custom-derived frequencies. We calculated cPRA scores for every hematopoietic stem cell transplantation (HSCT) patient at our institution based on the United Network for Organ Sharing (UNOS) frequencies and local frequencies. We compared frequencies and correlations between the calculators, segmented by gender. Finally, we put all scores into three buckets (mild, moderate, and high sensitizations) and looked at intergroup movement. RESULTS: 2531 patients that underwent HSCT at our institution had at least 1 antibody and were included in the analysis. Overall, the difference in medians between each group's UNOS cPRA and local cPRA was statistically significant, but highly correlated (UNOS vs. local total: 0.249 and 0.243, ρ = 0.994; UNOS vs. local female: 0.474 and 0.463, ρ = 0.987, UNOS vs. local male: 0.165 and 0.141, ρ = 0.996; P < 0.001 for all comparisons). The median difference between UNOS and cPRA scores for all patients was low (male: 0.014, interquartile range [IQR]: 0.004-0.029; female: 0.0013, IQR: 0.003-0.028). Placement of patients into three groups revealed little intergroup movement, with 2.96% (75/2531) of patients differentially classified. CONCLUSIONS: cPRA scores using local frequencies were modestly but significantly different than those obtained using national HLA frequencies. We released our software as open source, so other groups can calculate cPRA scores from national or custom-derived frequencies. Further investigation is needed to determine whether a local-HLA frequency approach can improve outcomes in patients who are immune-refractory to platelets.

Preformed Donor-specific Antibodies Against HLA Class II and Graft Outcomes in Deceased-donor Kidney Transplantation.

BACKGROUND: Many kidney transplant centers in the United States report both HLA class I and II antibodies detected by sensitive solid-phase assays (SPAs) to United Network for Organ Sharing as unacceptable antigens, significantly reducing the compatible donor organ pool and prolonging waiting time for highly sensitized patients. However, the clinical relevance of all detected donor-specific antibodies (DSAs) by SPA is not unequivocal, because fluorescence intensity does not always accurately reflect antibody pathogenicity. Our center does not exclude patients from transplantation based on DSA class II. METHODS: We performed a retrospective analysis in 179 deceased-donor kidney transplant recipients with solely DSA class II before transplant and patients without DSA and compared graft survival, rejection, and clinical outcomes. Patient survival was also compared with matched controls on the waiting list. RESULTS: Patients transplanted with DSA class II showed a clear survival benefit compared with matched patients who remained on dialysis or were waitlisted on dialysis/transplanted at 5 years (100%, 34%, and 73%, respectively). After a mean follow-up of 5.5 years, there was no significant difference in death-censored graft survival between transplanted patients without DSA and those with preformed DSA class II (adjusted HR 1.10; 95% confidence interval, 0.41-2.97), although the incidence of rejection was higher in recipients with DSA class II (adjusted HR 5.84; 95% confidence interval, 2.58-13.23; P < 0.001). Serum creatinine levels at 1, 3, and 5 years posttransplant did not differ between groups. No predictors of rejection were found, although patients who received basiliximab induction therapy had higher incidence of rejection (100%) compared with those who received antithymocyte globulin (52%). CONCLUSIONS: We conclude that for highly sensitized patients, deceased-donor kidney transplantation with DSA class II yields a survival benefit over prolonged waiting time on dialysis. Instead of listing DSA class II as unacceptable antigens, an individual approach with further immunologic risk assessment is recommended.

Association of Cold Ischemia Time With Acute Renal Transplant Rejection.

BACKGROUND: Kidney transplantation holds much promise as a treatment of choice for patients with end-stage kidney disease. The impact of cold ischemia time (CIT) on acute renal transplant rejection (ARTR) remains to be fully studied in a large cohort of renal transplant patients. METHODS: From the Organ Procurement and Transplantation Network database, we analyzed 63 798 deceased donor renal transplants performed between 2000 and 2010. We assessed the association between CIT and ARTR. We also evaluated the association between recipient age and ARTR. RESULTS: Six thousand eight hundred two (11%) patients were clinically diagnosed with ARTR. Longer CIT was associated with an increased risk of ARTR. After multivariable adjustment, compared with recipients with CIT < 12 hours, the relative risk of ARTR was 1.13 (95% confidence interval, 1.04-1.23) in recipients with CIT ≥ 24 hours. The association of CIT and ARTR was more pronounced in patients undergoing retransplantation: compared with recipients with CIT less than 12 hours, the relative risk of ARTR was 1.66 (95% confidence interval, 1.01-2.73) in recipients with CIT of 24 hours or longer. Additionally, older age was associated with a decreased risk of ARTR. Compared with recipients aged 18 to 29 years, the relative risk of ARTR was 0.50 (95% confidence interval, 0.45-0.57) in recipients 60 years or older. Longer CIT was also associated with increased risk of death-censored graft loss. Compared with recipients with CIT less than 12 hours, the hazard ratio of death-censored graft loss was 1.22 (95% confidence interval, 1.14-1.30) in recipients with CIT of 24 hours or longer. CONCLUSIONS: Prolonged CIT is associated with an increased risk of ARTR and death-censored graft loss. Older age was associated with a lower risk of ARTR.

A simple questionnaire to detect chronic kidney disease patients from Long An province screening data in Vietnam.

BACKGROUND: The prevalence of chronic kidney disease (CKD) in rural Vietnam is unknown. We wished to determine the prevalence of CKD and determine whether a simple questionnaire was able to detect individuals at high risk of CKD before expensive confirmatory laboratory testing. METHODS: A cross sectional study was performed. We recruited 2037 participants from 13 communes of Long An province, Vietnam, for CKD screening with urine albumin/creatinine ratio (ACR) measured by immunoturbidimetric method and serum creatinine to estimate glomerular filtration rate (eGFR). CKD was defined as either ACR ≥ 30 mg/g or eGFR MDRD < 60 ml/min/1.73 m2. A two page questionnaire with 23 variables was administered to each participant with queries postulated to be correlated with risk of CKD. RESULTS: Of the 2037 participants, 260 (12.76%) were found to have CKD. Five questionnaire variables (age more than 50, measured hypertension, history of diabetes, history of hypertension, and history of a low salt diet) were correlated with CKD, and used to construct a risk score for CKD. CONCLUSIONS: CKD is common in Vietnam. Our questionnaire and risk score tool can be used to detect individuals with a higher likelihood of CKD, and who can then be more economically screened with routine laboratory confirmatory tests.

Antibodies against HLA-DP recognize broadly expressed epitopes.

HLA matching and avoidance of pre-transplant donor-specific antibodies are important in selection of donors for solid organ transplant. Solid phase testing with single antigen beads allows resolution of antibody reactivity to the level of the allele. Single antigen bead testing results at a large transplant center were reviewed to identify selective reactivity patterns of anti-HLA antibodies. Many HLA-DP antibodies were identified in the context of other HLA antibodies, but some sera had antibodies against only HLA-DP. B cell flow crossmatch testing was positive for 2 out of 9 sera with HLA-DP antibodies. Many patterns of reactivity corresponded to epitopes in hypervariable regions C and F of DPB1, but some matched epitopes in other regions or DPA1. Through analysis of single antigen bead testing from a large number of patients, we report that anti-HLA-DP antibodies predominantly recognize broadly cross-reactive epitopes. The United Network for Organ Sharing has mandated HLA-DP typing on all deceased kidney donors, and HLA-DP epitopes should be considered as the major antigens for avoidance of pre-transplant donor-specific antibodies.

Fatal autoimmunity in mice reconstituted with human hematopoietic stem cells encoding defective FOXP3.

Mice reconstituted with a human immune system provide a tractable in vivo model to assess human immune cell function. To date, reconstitution of murine strains with human hematopoietic stem cells (HSCs) from patients with monogenic immune disorders have not been reported. One obstacle precluding the development of immune-disease specific "humanized" mice is that optimal adaptive immune responses in current strains have required implantation of autologous human thymic tissue. To address this issue, we developed a mouse strain that lacks murine major histocompatibility complex class II (MHC II) and instead expresses human leukocyte antigen DR1 (HLA-DR1). These mice displayed improved adaptive immune responses when reconstituted with human HSCs including enhanced T-cell reconstitution, delayed-type hypersensitivity responses, and class-switch recombination. Following immune reconstitution of this novel strain with HSCs from a patient with immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, associated with aberrant FOXP3 function, mice developed a lethal inflammatory disorder with multiorgan involvement and autoantibody production mimicking the pathology seen in affected humans. This humanized mouse model permits in vivo evaluation of immune responses associated with genetically altered HSCs, including primary immunodeficiencies, and should facilitate the study of human immune pathobiology and the development of targeted therapeutics.

Human leukocyte antigen typing using a knowledge base coupled with a high-throughput oligonucleotide probe array analysis.

Human leukocyte antigens (HLA) are important biomarkers because multiple diseases, drug toxicity, and vaccine responses reveal strong HLA associations. Current clinical HLA typing is an elimination process requiring serial testing. We present an alternative in situ synthesized DNA-based microarray method that contains hundreds of thousands of probes representing a complete overlapping set covering 1,610 clinically relevant HLA class I alleles accompanied by computational tools for assigning HLA type to 4-digit resolution. Our proof-of-concept experiment included 21 blood samples, 18 cell lines, and multiple controls. The method is accurate, robust, and amenable to automation. Typing errors were restricted to homozygous samples or those with very closely related alleles from the same locus, but readily resolved by targeted DNA sequencing validation of flagged samples. High-throughput HLA typing technologies that are effective, yet inexpensive, can be used to analyze the world's populations, benefiting both global public health and personalized health care.

Donor chimerism early after reduced-intensity conditioning hematopoietic stem cell transplantation predicts relapse and survival.

The impact of early donor cell chimerism on outcomes of T cell-replete reduced-intensity conditioning (RIC) hematopoietic stem cell transplantation (HSCT) is ill defined. We evaluated day 30 (D30) and 100 (D100) total donor cell chimerism after RIC HSCT undertaken between 2002 and 2010 at our institution, excluding patients who died or relapsed before D30. When available, donor T cell chimerism was also assessed. The primary outcome was overall survival (OS). Secondary outcomes included progression-free survival (PFS), relapse, and nonrelapse mortality (NRM). We evaluated 688 patients with hematologic malignancies (48% myeloid and 52% lymphoid) and a median age of 57 years (range, 18 to 74) undergoing RIC HSCT with T cell-replete donor grafts (97% peripheral blood; 92% HLA-matched), with a median follow-up of 58.2 months (range, 12.6 to 120.7). In multivariable analysis, total donor cell and T cell chimerism at D30 and D100 each predicted RIC HSCT outcomes, with D100 total donor cell chimerism most predictive. D100 total donor cell chimerism <90% was associated with increased relapse (hazard ratio [HR], 2.54; 95% confidence interval [CI], 1.83 to 3.51; P < .0001), impaired PFS (HR, 2.01; 95% CI, 1.53 to 2.65; P < .0001), and worse OS (HR, 1.50; 95% CI, 1.11 to 2.04, P = .009), but not with NRM (HR, .76; 95% CI, .44 to 2.27; P = .33). There was no additional utility of incorporating sustained D30 to D100 total donor cell chimerism or T cell chimerism. Low donor chimerism early after RIC HSCT is an independent risk factor for relapse and impaired survival. Donor chimerism assessment early after RIC HSCT can prognosticate for long-term outcomes and help identify high-risk patient cohorts who may benefit from additional therapeutic interventions.

The combined risk of donor quality and recipient age: higher-quality kidneys may not always improve patient and graft survival.

BACKGROUND: The Kidney Donor Profile Index (KDPI) is a more precise donor organ quality metric replacing age-based characterization of donor risk. Little prior attention has been paid on the outcomes of lower-quality kidneys transplanted into elderly recipients. Although we have previously shown that immunological risks associated with older organs are attenuated by advanced recipient age, it remains unknown whether risks associated with lower-quality KDPI organs are similarly reduced in older recipients. METHODS: Donor organ quality as measured by the KDPI was divided into quintiles (very high, high, medium, low, and very low quality), and Cox proportional hazards was used to assess graft and recipient survival in first-time adult deceased donor transplant recipients by recipient age. RESULTS: In uncensored graft survival analysis, recipients older than 69 years had demonstrated comparable outcomes if they received low-quality kidneys compared to medium-quality kidneys. Death-censored analysis demonstrated no increased relative risk when low-quality kidneys were transplanted into recipients aged 70 to 79 years (hazard ratio [HR], 1.11; P=0.19) or older than 79 years (HR, 1.08; P=0.59). In overall survival analysis, elderly recipients gained no relative benefit from medium-quality kidneys over low-quality kidneys (70-79 years: HR, 1.03, P=0.51; >79 years: HR, 1.08; P=0.32). CONCLUSION: Our analysis demonstrates that transplanting medium-quality kidneys into elderly recipients does not provide significant advantage over low-quality kidneys.

Impact of pretransplant anti-HLA antibodies on outcomes in lung transplant candidates.

RATIONALE: The prevalence of anti-HLA antibodies in lung transplant candidates and their impact on waitlist and transplant outcomes is not known. OBJECTIVES: We examined the prevalence of pretransplant anti-HLA antibodies at varying thresholds and evaluated their impact on outcomes before and after lung transplantation. METHODS: We performed a single-center retrospective cohort study including all patients listed for lung transplantation between January 2008 and August 2012. Per protocol, transplant candidates were assessed by solid phase LABscreen mixed Class I and II and LABscreen Single Antigen assays. MEASUREMENTS AND MAIN RESULTS: Among 224 patients, 34% had anti-HLA antibodies at mean fluorescent intensity (MFI) greater than or equal to 3,000 (group III), and 24% had antibodies at MFI 1,000 to 3,000 (group II). Ninety percent of the patients with pretransplant anti-HLA antibodies had class I antibodies, whereas only seven patients developed class II alone. Patients in group III were less likely to receive transplants than patients without any anti-HLA antibodies (group I) (45.5 vs. 67.7%, P = 0.005). Wait time to transplant was longer in group III than group I, although this difference did not meet statistical significance, and waitlist mortality was similar. Among transplant recipients, antibody-mediated rejection (AMR) was more frequent in group III than in group II (20% vs. 0%, P = 0.01) or group I (6.3%, P = 0.05). CONCLUSIONS: The presence of anti-HLA antibodies at the high MFI threshold (>3,000) was associated with lower transplant rate and higher rates of AMR. Screening for anti-HLA antibodies using the 3,000 MFI threshold may be important in managing transplant candidates and recipients.

Longitudinal trends and influence of BMI mismatch in living kidney donors and their recipients.

BACKGROUND AND OBJECTIVES: Age and body mass index (BMI) of kidney donors and recipients affect kidney allograft outcomes. Moreover, while deceased donor and recipient body size mismatch have been reported to influence allograft outcomes, how BMI mismatch in living kidney donor-recipient pairs affect graft survival is not well defined. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: We investigated trends in characteristics of 90,815 US. living kidney donors and their recipients between 1987 and 2008. RESULTS: Median ages of donors and their recipients have risen over time, and the proportion of living donors age ≥ 50 years increased from 11 to 25%. Median BMI of recipients increased from 22.6 to 26.6 kg/m(2); median BMI of kidney donors for the past 5 years has been 26.4 kg/m(2). Only 35% of living donor-recipient pairs were in the same BMI category (<25, 25-29.9, 30-34.9, or ≥ 35 kg/m(2)). BMI mismatch where the living donor was three categories heavier than the recipient was associated with a significant adjusted risk for death-censored allograft loss (HR 2.31, 95% CI 1.05-5.08). CONCLUSIONS: Living kidney donors are donating at more advanced ages, and the majority are overweight or obese in recent years. In summary: (1) previous longitudinal studies of living kidney donor outcomes may not be generalizable to recent donors, and studies of contemporary living kidney donor cohorts may be informative, (2) the majority of living donor-recipient pairs have BMI mismatch, and (3) extreme BMI mismatch where the living donor is heavier may confer an independent risk for allograft loss.

A pilot study on the immunological effects of oral administration of donor major histocompatibility complex class II peptides in renal transplant recipients.

Oral tolerance is an important physiological mechanism of immune hyporesponsiveness to dietary antigens and the commensal flora of the gastrointestinal tract. Feeding of alloantigens, therefore, has the potential to suppress undesirable immune responses after transplantation. To date, there are no published reports on the effects of such an approach in human transplant recipients. In the present pilot study, we demonstrate complete suppression of baseline indirect alloreactivity in patients with chronic renal allograft dysfunction following the oral feeding of low (0.5 mg/d) but not higher (1.0 and 5.0 mg/d) doses of donor major histocompatibility complex (MHC) class II peptides. The regimen was well tolerated with no evidence for sensitization to the donor antigen. Our results indicate that oral feeding of low dose donor MHC peptide may represent a safe and effective therapy to suppress indirect alloreactivity in renal transplant recipients with chronic allograft dysfunction and warrants further clinical investigation.

HLA-DR alpha 2 mediates negative signalling via binding to Tirc7 leading to anti-inflammatory and apoptotic effects in lymphocytes in vitro and in vivo.

Classically, HLA-DR expressed on antigen presenting cells (APC) initiates lymphocyte activation via presentation of peptides to TCR bearing CD4+ T-Cells. Here we demonstrate that HLA-DR alpha 2 domain (sHLA-DRalpha2) also induces negative signals by engaging TIRC7 on lymphocytes. This interaction inhibits proliferation and induces apoptosis in CD4+ and CD8+ T-cells via activation of the intrinsic pathway. Proliferation inhibition is associated with SHP-1 recruitment by TIRC7, decreased phosphorylation of STAT4, TCR-zeta chain & ZAP70, and inhibition of IFN-gamma and FasL expression. HLA-DRalpha2 and TIRC7 co-localize at the APC-T cell interaction site. Triggering HLA-DR - TIRC7 pathway demonstrates that sHLA-DRalpha2 treatment inhibits proinflammatory-inflammatory cytokine expression in APC & T cells after lipopolysaccaride (LPS) stimulation in vitro and induces apoptosis in vivo. These results suggest a novel antiproliferative role for HLA-DR mediated via TIRC7, revise the notion of an exclusive stimulatory interaction of HLA-DR with CD4+ T cells and highlights a novel physiologically relevant regulatory pathway.

T-cell immune response cDNA 7 in allograft rejection and inflammation.

The membrane protein T-cell immune response cDNA 7 (TIRC7) is transiently expressed in subsets of lymphocytes following antigen stimulation. The importance of TIRC7 in immune activation is demonstrated by the effect of antibodies directed against extracellular domains of TIRC7. In vitro targeting of TIRC7 inhibits proliferation and cytokine expression in human, mouse and rat lymphocytes, and these inhibitory effects have been associated with induction of cytotoxic T-lymphocyte antigen 4 mRNA and protein in the presence of TIRC7 antibodies. In vivo, anti-TIRC7 antibodies prevent kidney transplant rejection in rats and heart allograft rejection in mice. Treatment with an anti-TIRC7 antibody as monotherapy or in combination with TNFalpha blockade inhibits disease progression in collagen-induced arthritis. TIRC7 expression decreases in the peripheral blood of humans who have undergone cardiac transplant prior to clinical rejection, and is therefore a promising noninvasive tool for the prediction of rejection. Thus, targeting of TIRC7 may lead to the development of specific and effective therapeutic and diagnostic approaches by unifying relevant cellular and molecular responses in T- and B-cell subsets, and represents a promising new pathway for immune regulation in transplantation and autoimmune disease.

Predictors of improved progression-free survival after nonmyeloablative allogeneic stem cell transplantation for advanced chronic lymphocytic leukemia.

Although chronic lymphocytic leukemia (CLL) remains an incurable disease with standard chemotherapy, the appropriate role and timing of transplantation are unclear. In this analysis, we report the outcomes of 46 patients with advanced CLL who underwent nonmyeloablative stem cell transplantation (NST) from HLA-matched unrelated (67%) or related (33%) donors. Fludarabine (30 mg/m2 x 4) and low-dose intravenous busulfan (0.8 mg/kg/day x 4) were used for conditioning. The 2-year overall survival (OS) and progression-free survival (PFS) rates in this refractory patient population were 54% and 34%, respectively, with a median follow-up of 20 months. The primary cause of treatment failure was relapse, with a 2-year cumulative incidence of 48%. High hematopoietic donor chimerism > or = 75% at day +30 was a significant predictor of 2-year PFS (47% vs 11%; P = .03). In multivariate analysis, chemotherapy-refractory disease at transplantation was associated with a 3.2-fold risk of progression (P = .01) and a 4.6-fold risk of death (P = .02). Increasing number of previous therapies and increasing bone marrow involvement were also associated with decreased PFS and OS. These results suggest that NST using fludarabine and low-dose intravenous busulfan is a reasonable treatment option for patients with advanced CLL, but that NST earlier in the disease course will likely be needed to achieve long-term disease control in a high proportion of patients.

The HLDA8 blind panel: findings and conclusions.

There were over 600 antibodies submitted to HLDA8, with many of unknown specificity. Of these, 101 antibodies were selected for a blind panel study that also included 5 negative controls and 27 positive controls of known CD specificity making a total of 133 antibodies in the final panel. Of the 101 unknowns, 31 antibodies were identified during the course of this blind panel study as being specific for known molecules and included some specific for MHC class II antigens, CD45 isoforms and the Dombrock antigen. Several antibody pairs among those in the blind panel were found to have very similar staining patterns and were therefore compared by immunohistochemical and/or Western blot analyses for identity.

TIRC7 pathway as a target for preventing allograft rejection.

A number of leukocyte surface molecules play an essential role during immune activation. Targeting of these molecules utilizing antibodies serves as a specific therapeutic approach for the treatment of a variety of human diseases. Antibodies targeting a number of leukocyte surface molecules were shown to induce tolerance to transplants in several animal models. A novel membrane molecule, T-cell immune response cDNA 7 (TIRC7), has been shown to be an essential protein in the regulation of lymphocyte activation. TIRC7 does not share any homology with other known membrane proteins expressed during the course of lymphocyte activation and does not belong to any of the known costimulatory, cytokine, chemokine or receptor families. TIRC7, a highly conserved protein across species, is expressed in immune tissues such as spleen, lymph nodes, and T and B lymphocytes. Antibodies against extracellular domains of TIRC7 prolong allograft survival in rat and mouse transplantation models. The prevention of rejection is mediated at least partially via induction of cytotoxic T lymphocyte antigen 4 (CTLA4) in T cells. Functional cellular assays utilizing TIRC7-deficient mice splenocytes show that TIRC7 does have an impact not only on T-cell, but also on B-cell response. Subtherapeutic amounts of FK506 and anti-TIRC7 monoclonal antibody prolong graft survival, suggesting synergistic effects with calcineurin inhibitors. Targeting TIRC7 with monoclonal antibody might serve as a promising therapeutic strategy for preventing allograft rejection in humans and treatment of other immune-related diseases. Acutely rejected human kidney allografts show strong expression of TIRC7 despite treatment with calcineurin inhibitors. Therefore, monitoring TIRC7 expression may facilitate an early diagnostic tool of acute rejection. TIRC7 seems to belong to a group of targets with dual roles in disease pathogenesis, so-called theranostics, which can be utilized to treat and diagnose diseases.