Relationship between plasma rabbit anti-thymocyte globulin concentration and immunosuppressive therapy response in patients with severe aplastic anemia.

OBJECTIVES: Patients with acquired aplastic anemia (AA) without HLA-matched sibling donors or aged >40 years receive immunosuppressive therapy (IST) with anti-thymocyte globulin (ATG). We investigated the relationship between plasma rabbit ATG (r-ATG) concentration and IST response. METHODS: From May 2012 to October 2017, 81 patients with severe AA who required initial IST were included. A 1:1 block randomization was employed for 2.5 and 3.5 mg/kg doses of r-ATG. RESULTS: No significant difference in response rates was observed between the 2.5 and 3.5 mg/kg groups (63% vs. 58%, P = .894). Median r-ATG concentrations on days 14 and 28 after IST were 15.2 (0.0-97.7) and 1.8 (0.0-74.9 µg/mL), respectively. According to r-ATG concentration, response rates were significantly higher in the group with higher r-ATG concentration than in those with lower r-ATG concentration (day 14, 88% vs. 52%; P = .006 and day 28, 79% vs. 46%; P = .005). In multivariate analysis, higher r-ATG concentrations at day 28 were independent predictors of favorable response to IST at 6 months (odds ratio, 0.29; 95% confidence interval, 0.09-0.93; P = .037). CONCLUSIONS: The present data indicate that higher r-ATG concentration at day 28 resulted in improved IST response.

Correlation of rabbit antithymocyte globulin serum levels and clinical outcomes in children who received hematopoietic stem cell transplantation from an alternative donor.

We analyzed the correlation between rabbit ATG (rATG) serum levels and clinical outcomes in 37 children who received rATG at a total dose of 10 or 15 mg/kg during HSCT conditioning from an alternative donor. Fourteen patients had advanced malignant diseases, 13 had severe AA, and 10 had inherited disorders. Complete engraftment was achieved in all patients, and no rejection occurred. The cumulative incidence of grades II-IV acute GVHD and extensive chronic GVHD was 27% (95% CI, 12.5-39.6%) and 8.1% (95% CI, 0-23.1%), respectively. Multivariate analysis identified lower rATG levels at week 4 as an independent risk factor in the development of grades II-IV acute GVHD (p = 0.037). Serious infections were not observed in any patient following HSCT. No correlation was found between EBV reactivation and rATG levels at week 2 and week 4 after HSCT. Furthermore, no correlation was found between relapse and rATG levels two and four wk post-transplantation. The probability of five-yr OS among patients was 70.3% (95% CI, 59.8-79.2%). Our results suggest that targeted rATG administration may protect patients from severe acute GVHD without increasing the risk of EBV reactivation or relapse.

Immune reconstitution after anti-thymocyte globulin-conditioned hematopoietic cell transplantation.

BACKGROUND AIMS: Anti-thymocyte globulin (ATG) is being used increasingly to prevent graft-versus-host disease (GvHD); however, its impact on immune reconstitution is relatively unknown. We (i) studied immune reconstitution after ATG-conditioned hematopoietic cell transplantation (HCT), (ii) determined the factors influencing the reconstitution, and (iii) compared it with non-ATG-conditioned HCT. METHODS: Immune cell subset counts were determined at 1-24 months post-transplant in 125 HCT recipients who received ATG during conditioning. Subset counts were also determined in 46 non-ATG-conditioned patients (similarly treated). RESULTS: (i) Reconstitution after ATG-conditioned HCT was fast for innate immune cells, intermediate for B cells and CD8 T cells, and very slow for CD4 T cells and invariant natural killer T (iNKT) (iNKT) cells. (ii) Faster reconstitution after ATG-conditioned HCT was associated with a higher number of cells of the same subset transferred with the graft in the case of memory B cells, naive CD4 T cells, naive CD8 T cells, iNKT cells and myeloid dendritic cells; lower recipient age in the case of naive CD4 T cells and naive CD8 T cells; cytomegalovirus recipient seropositivity in the case of memory/effector T cells; an absence of GvHD in the case of naive B cells; lower ATG serum levels in the case of most T-cell subsets, including iNKT cells; and higher ATG levels in the case of NK cells and B cells. (iii) Compared with non-ATG-conditioned HCT, reconstitution after ATG-conditioned HCT was slower for CD4 T cells, and faster for NK cells and B cells. CONCLUSIONS: ATG worsens the reconstitution of CD4 T cells but improves the reconstitution of NK and B cells.

Evaluation of three different laboratory methods to detect preformed human leukocyte antigen antibodies in a South African kidney transplant population.

BACKGROUND: Anti-human leukocyte antigen antibodies (anti-HLA) play a crucial role in graft. Detection of anti-HLA, both pre- and post-transplant is a crucial investigation in clinical organ transplantation. OBJECTIVES: Three methodologies for the detection of lymphocytotoxic antibodies were compared to establish which of these is best suited to optimise pre-transplant donor-recipient matching. METHODS: Serum samples from 15 renal transplant patients were tested for the presence of anti-HLA by i) cytotoxic-dependent cross-match (CDCXM), ii) flow cytometric cross-match (FCXM) and iii) Luminex-based donor specific antibody cross-match (DSAXM) method, Confirmatory tests for the presence of preformed HLA antibodies were tested using Luminex methodology. RESULTS: Two (13%) of the 15 patients had positive HLA Class I antibodies (Ab) using all 3 methods. An additional 2 HLA Class I Ab were identified with FCXM/CDCXM. DSAXM identified 1 HLA Class I positive, not indicated by CDCXM/FCXM.High HLA Class II positivity (40%), identified by CDCXM, while DSAXM and FCXM identified two and one patients, respectively. CDCXM produced 4 false-positive results confirmed by lymphocyte single antigen (LSA) assay. CONCLUSIONS: The DSAXM method appears to add value in pre-transplantation screening to identify pre-sensitised patients that may not reject the donor graft due to the absence of donor-specific antibodies.

Removal of Anti-Thymocyte Globulin by Plasma Exchange in ABO-Incompatible and Positive Crossmatch Kidney Transplant Recipients.

BACKGROUND: Recipients of ABO-incompatible (ABOI) and positive crossmatch (PXM) kidney transplants are at high risk for antibody-mediated acute rejection. Despite aggressive immunosuppression in high-risk patients, the incidence of acute rejection remains considerably higher than in other groups. No published studies have examined plasma concentrations of anti-thymocyte globulin (ATG) in patients undergoing plasma exchange. The objectives of this study were to compare plasma ATG concentrations before and after plasma exchange in ABOI and PXM kidney transplant patients to determine the amount removed. MATERIALS AND METHODS: This prospective pharmacokinetic evaluation enrolled 10 patients undergoing ABOI or PXM kidney transplant at an academic medical center. Blood and waste plasma samples from 5 patients were assayed for total and active ATG concentrations. Patient records were monitored for renal function and rejection rates in the first 6 months post-transplant. RESULTS: Total ATG concentrations decreased a mean of 59.78 ± 13.91% after each plasma exchange session, and active ATG levels decreased a mean of 56.8 ± 17.08%. Mean daily concentrations reflect a lack of expected ATG accumulation. Only 1 of 4 patients had detectable ATG concentrations after 30 days. After 6 months, the incidence of acute rejection in this sample was 44% and graft survival was 89%. CONCLUSIONS: This is the first study to show that plasma exchange removes a substantial amount of ATG in high-risk kidney transplant patients. Based on these results, we believe these high-risk patients have been traditionally underdosed.

High rabbit-antihuman thymocyte globulin levels are associated with low likelihood of graft-vs-host disease and high likelihood of posttransplant lymphoproliferative disorder.

Rabbit-antithymocyte globulin (ATG) given with conditioning has the potential to decrease the likelihood of graft-versus-host disease (GVHD) or graft failure and to increase the likelihood of relapse or infections. After a given ATG dose, serum ATG levels are variable. Here we determined ATG levels on days 7 and 28 in 153 patients whose conditioning included 4.5 mg/kg ATG (thymoglobulin). Median follow-up was 547 days (range: 14-1519, minimum for patients who have not died, relapsed, developed second malignancy, or had graft failure, 365). Both high day 7 levels and high day 28 levels were associated with low likelihoods of grade II-IV acute GVHD and chronic GVHD needing systemic immunosuppressive therapy, and a high likelihood of posttransplant lymphoproliferative disorder (PTLD). Patients with day 7 ATG levels above 0.803 mg/L had 0.52-fold risk of developing chronic GVHD needing systemic therapy (P = 0.012) and patients with day 7 ATG levels above 1.436 mg/L had 5.84-fold risk of developing PTLD (P = 0.001) compared to patients with lower ATG levels. There was no association of ATG levels with relapse, death, or non-PTLD infections. Association with graft failure could not be evaluated due to only 4 graft failures in the cohort. In conclusion, patients with slow clearance of ATG have a low risk of GVHD, but a high risk of PTLD. The clearance of this relatively low dose of ATG does not impact the likelihood of relapse, death, or non-PTLD infections.

The Relationship between High Iodine Consumption and Levels of Autoimmune Thyroiditis-Related Biomarkers in a Chinese Population: a Meta-Analysis.

To comprehensively evaluate the relationship between high iodine concentration and biomarker abnormalities related to autoimmune thyroiditis in a Chinese population. Medline, PubMed, and Embase electronic databases were searched for articles published domestically and internationally on the relationship between high iodine concentrations and thyroid hormone antibodies and thyroid-stimulating hormone in China before March 2019. Articles published in Chinese were searched in the China Biology Medicine (CBM) disc, Wanfang Database, and China National Knowledge Infrastructure (CNKI). A total of 16 cross-sectional articles were included in this study, including 9061 participants. A meta-analysis was conducted in Stata 14.0. The binary categorical and continuous variables used odds ratios (ORs) and standardized mean differences (SMDs) with the corresponding 95% confidence intervals (CIs) as the effect statistics, respectively. The results showed that high iodine concentrations had a minimal association with the abnormal rates of thyroid peroxidase antibody (TPOAb) (OR = 1.274, 95% CI (0.957, 1.695), P > 0.05) and thyroglobulin antibody (TGAb) (OR = 1.217, 95% CI (0.911, 1.626), P > 0.05) in the entire population. The thyroid-stimulating hormone (TSH) level in the high iodine group was greater than that in the adaptive iodine group (SMD = 0.202, 95% CI (0.096, 0.309), P < 0.05). The results of the subgroup analysis showed that the abnormal TPOAb rate in pregnant women (OR = 1.519, 95% CI (1.007, 2.291), P < 0.05) and children (OR = 3.365, 95% CI (1.966, 5.672), P < 0.05) in the high iodine group was greater than that in the adaptive iodine group, and the abnormal TGAb rate of children in the high iodine group was greater than that in the adaptive iodine group. The TSH levels of lactating women (SMD = 0.24, 95% CI (0.053, 0.427), P < 0.05), pregnant women (SMD = 0.301, 95% CI (0.176, 0.426), P < 0.05), and children (SMD = 0.25, 95% CI(0.096, 0.309), P < 0.05) in the high iodine group were higher than those in the adaptive iodine group. Egger's and Begg's tests showed no significant (P > 0.1) publication bias. High iodine can increase the risk of abnormal levels of TPOAb, TGAb, and TSH related to autoimmune thyroiditis in pregnant women, lactating women, and children in China.

Quantification of T Cell Binding Polyclonal Rabbit Anti-thymocyte Globulin in Human Plasma with Liquid Chromatography Tandem-Mass Spectrometry.

The addition of rabbit anti-human thymocyte globulin (ATG) to the conditioning regimen prior to allogeneic hematopoietic cell transplantation has significantly reduced the risk of graft-versus-host disease (GvHD) and graft failure. However, ATG has a small therapeutic window. Overexposure of ATG post-HCT hampers T cell immune reconstitution and has been associated with increased relapse rates and viral reactivations, whereas underexposure has been associated with an increased incidence of GvHD, both of which lead to increased mortality. Therapeutic drug monitoring of T cell binding ATG plasma levels provides a means to optimize dosing for patients at high risk for graft failure to ensure timely T cell immune reconstitution and subsequently increase survival chances. This manuscript describes the first liquid chromatography tandem-mass spectrometry (LC-MS/MS) method to quantify the pharmacologically active fraction of polyclonal ATG in plasma. This was achieved through immunoaffinity purification of active ATG from plasma with Jurkat T cells. After the binding and washing, samples were eluted, denatured, and trypsin-digested. Signature peptides originating from the IgG constant chain were measured with LC-MS/MS. Critical method parameters were optimized, and the method was successfully validated following European Medicines Agency (EMA) guidelines. The method covered the therapeutic range of ATG and was validated at a lower limit of quantification (LLOQ) of 1 AU/mL with an overall CV and bias of 11.8% and - 2.5%, respectively. In conclusion, we developed a LC-MS/MS-based method to quantify active polyclonal rabbit ATG in human plasma. We suggest that this novel assay can be used to monitor and optimize dosing of ATG in clinical practice.

DSA-FXM: Accelerated Donor-specific Flow Crossmatch Discriminating Class I and II Antibody Specifically and Only to Donor HLA for Determining True Incompatibility.

BACKGROUND: Worldwide, a final crossmatch is the gold standard for determining compatibility between patient and donor before solid organ transplantation and preventing hyperacute rejection. In the absence of autoantibodies, an incompatible crossmatch in a sensitized patient is attributed to mismatched donor HLA. However, current physical crossmatch methods cannot distinguish reactivity to HLA from other clinically irrelevant cell surface targets nor the class of HLA if it is the target. Result interpretation is difficult or impossible when autoantibodies, alloantibodies, or therapeutic antibodies coexist. METHODS: Herein, we describe a unique donor-specific flow crossmatch (DSA-FXM) that distinguishes HLA class I or II donor-specific antibody bound to HLA antigens on the donor cell surface in their native conformation that is not impacted by rituximab, anti-thymocyte globulin (after absorption), or autoantibodies. It is HLA specific. RESULTS: We compared the results of single-antigen antibody testing, autoreactive and alloreactive flow cytometry crossmatches (FXM) using traditional FXM and our DSA-FXM method from 94 patients (enriched for auto+/allo+ pairs; n = 64) against 110 donors (338 tests) and show that, in our cohort, positive traditional FXM results are not directed to donor HLA 60.25% of the time and negative traditional FXM results are missing HLA donor-specific antibody 36.2% of the time based on the DSA-FXM. CONCLUSIONS: We demonstrate that the DSA-FXM is able to define categorically distinct and clinically important HLA antibody profiles in half the time required for the standard FXM, potentially shortening cold ischemia time and providing clinicians with unambiguous essential information regarding HLA compatibility when time is critical.

Total and active rabbit antithymocyte globulin (rATG;Thymoglobulin) pharmacokinetics in pediatric patients undergoing unrelated donor bone marrow transplantation.

Rabbit antithymocyte globulin (rATG; Thymoglobulin) is currently used to prevent or treat graft-versus-host disease (GVHD) during hematopoietic stem cell transplantation (HSCT). The dose and schedule of rATG as part of the preparative regimen for unrelated donor (URD) bone marrow transplantation (BMT) have not been optimized in pediatric patients. We conducted a prospective study of 13 pediatric patients with hematologic malignancies undergoing URD BMT at St. Jude Children's Research Hospital from October 2003 to March 2005, to determine the pharmacokinetics and toxicities of active and total rATG. The conditioning regimen comprised total body irradiation (TBI), thiotepa, and cyclophosphamide (Cy); cyclosporine (CsA) and methotrexate (MTX) were administered as GVHD prophylaxis. Patients received a total dose of 10 mg/kg rATG, and serial blood samples were assayed for total rATG by enzyme linked immunosorbent assay (ELISA) and active rATG by florescein activated cell sorting (FACS). We found that our weight-based dosing regimen for rATG was effective and well tolerated by patients. The half-lives of total and active rATG were comparable to those from previous studies, and despite high doses our patients had low maximum concentrations of active and total rATG. There were no occurrences of grade iii-iv GVHD even in patients having low peak rATG levels, and the overall incidence of grade II GVHD was only 15%. None of the patients had serious infections following transplantation. These data support the use of a 10 mg/kg dose of rATG in children with hematologic malignancies because it can be administered without increasing the risk of graft rejection, or serious infection in pediatric patients with a low rate of GVHD. These conclusions may not apply to patients with nonmalignant disorders.

Role of complement in patients with autoimmune hemolytic anemia and platelet transfusion refractoriness.

The complement is a key player of the innate immune response. It provides defense mechanisms that are not specific, but very efficient at neutralizing any invader, accounting for 4% of the proteins in the peripheral blood. Nevertheless, there is a dark side to the complement system, as it may activate its machinery against healthy cells such as peripheral blood red blood cells and platelets resulting in undesired hemolysis and thrombocytopenia, respectively. Understanding and identifying the role of complement in these settings allow physicians to adjust their diagnostic and therapeutic modalities accordingly. The role of complement in the pathophysiology and management of autoimmune hemolytic anemia and of alloimmune-mediated thrombocytopenia is under investigation and discussed.

Clinical impact of human Jurkat T-cell-line-derived antithymocyte globulin in multiple myeloma patients undergoing allogeneic stem cell transplantation.

BACKGROUND: Antithymocyte globulin or human Jurkat T-cell-line-derived antilymphocyte globulin is used in allogeneic stem cell transplantation to induce in vivo T-cell depletion to facilitate engraftment and lower graft-versus-host disease. In vitro studies suggest that antithymocyte globulin, besides causing T-cell depletion, has strong anti-myeloma activity. DESIGN AND METHODS: We evaluated the anti-myeloma activity of antilymphocyte globulin in a melphalan/fludarabine-based reduced intensity conditioning regimen as well as the incidence of graft-versus-host disease in 138 multiple myeloma patients who underwent allogeneic stem cell transplantation with (n=79) or without (n=59) antilymphocyte globulin. RESULTS: Leukocyte and platelet engraftment were faster in the group not receiving antilymphocyte globulin (13 vs. 16 days, p<0.001 and 11 vs. 19 days, p< 0.001, respectively). Inclusion of antithymocyte globulin led to a better day 100 overall response rate (93% vs. 78%, p=0.03) and complete response rate (59% vs. 39%, p=0.04), to a lower incidence of both acute grade III/IV graft-versus-host-disease (11% vs. 22%, p=0.10) and chronic graft-versus-host disease (23% vs. 65%, p<0.001) and to a trend to improved event-free survival at 3 years (39% vs. 27%, p=0.5). There was no difference in the estimated cumulative incidence of treatment-related mortality at 1 year between the groups receiving or not antilymphocyte globulin (25% vs. 26%). In a multivariate analysis treatment with antilymphocyte globulin was the only significant factor for achievement of a complete remission (RR:2.57, p=0.02). CONCLUSIONS: Inclusion of antithymocyte globulin in allogeneic stem cell transplantation protocols for patients with multiple myeloma may increase remission rates and at the same time prevent graft-versus-host disease with no increase of relapses.

Anti-HLA Antibodies After Precocious Transplantectomy by Vascular Thrombosis.

BACKGROUND: Our objective in this study was to determine the effects of early renal transplantectomy on patients and the production of anti-human leukocyte antigen (anti-HLA) antibodies. METHODS: Between January 2003 and May 2017, we analyzed a group of patients for the presence of specific HLA class I and/or II donor-specific antibodies (DSA), their panel-reactive antibodies (PRA), and the time period in which the antibodies were still detectable after transplantectomy. RESULTS: Anti-HLA antibodies were detected in 60.8% of patients, 60.8% and 52.2% of those patients had anti-class I and anti-class II antibodies, respectively. DSA were detected in 91.7% of the anti-HLA class I patients. Class II DSA were detected all of the patients with anti-HLA class II antibodies. The average (mean ± SD) PRA levels in our patients after transplantectomy was 60 ± 34% in class I and 63 ± 36% in class II. CONCLUSION: Anti-HLA antibodies can be detected well after transplantectomy. Even if the kidney allograft had been transplanted for only a short time, when the intensity of immunosuppression was the highest, many patients developed anti-HLA antibodies. The patients who continued with immunosuppression after transplantectomy did not develop anti-HLA antibodies.

Long-term cell monitoring of kidney recipients after an antilymphocyte globulin induction with and without steroids.

BACKGROUND: Because of several side effects, the corticosteroid usage has been minimized in kidney transplantation. The increased acute rejection episodes associated with their withdrawal may counterbalance with induction treatment using polyclonal antilymphocyte globulin (ALG). The effects of ALG on blood cell phenotype have already been the subject of several reports. However, to date, no data are available concerning the comparison of blood phenotype when ALG is given with or without steroids and no gene profiling study has been performed. METHODS: We report here on a longitudinal blood cell analysis of a selected cohort of kidney recipients enrolled in a randomized study of steroid avoidance or withdrawal (during 6 months) during ALG induction. RESULTS: In the two groups, ALG quickly and massively depleted all the T cells and natural killer cells, but not B cells. Interestingly, the lymphopenia-driven homeostatic proliferation of CD4 and CD8T cells strongly differed with persistent low CD4 (including CD25CD4) T-cell counts. Effector memory CD8T cells reappeared rapidly. ALG induced apoptosis-associated molecules and increased myeloid cell genes. However, few genes were found differentially expressed with a low fold ratio between the two groups during and at distance of corticotherapy. CONCLUSION: Thus initial steroid avoidance or withdrawal associated with ALG induction has a weak influence on phenotype and transcriptional pattern of blood leukocytes. In contrast, ALG therapy induces an early and strong depletion of all T-cell subsets with contrasted long-lasting homeostatic regulation.

Identification of novel regulators in T-cell differentiation of aplastic anemia patients.

BACKGROUND: Aplastic anemia (AA) is a bone marrow failure syndrome mostly characterized by an immune-mediated destruction of marrow hematopoietic progenitor/stem cells. The resulting hypocellularity limits a detailed analysis of the cellular immune response. To overcome this technical problem we performed a microarray analysis of CD3+ T-cells derived from bone marrow aspirates and peripheral blood samples of newly diagnosed AA patients and healthy volunteers. Two AA patients were additionally analyzed after achieving a partial remission following immunosuppression. The regulation of selected candidate genes was confirmed by real-time RT-PCR. RESULTS: Among more than 22,200 transcripts, 583 genes were differentially expressed in the bone marrow of AA patients compared to healthy controls. Dysregulated genes are involved in T-cell mediated cytotoxicity, immune response of Th1 differentiated T-cells, and major regulators of immune function. In hematological remission the expression levels of several candidate genes tend to normalize, such as immune regulators and genes involved in proinflammatory immune response. CONCLUSION: Our study suggests a pivotal role of Th1/Tc1 differentiated T-cells in immune-mediated marrow destruction of AA patients. Most importantly, immune regulatory genes could be identified, which are likely involved in the recovery of hematopoiesis and may help to design new therapeutic strategies in bone marrow failure syndromes.

Removal of therapeutic anti-lymphocyte antibodies from human sera prior to anti-human leukocyte antibody testing.

Both monoclonal (e.g. Orthoclone (OKT3), rituximab) and polyclonal (e.g. ATGAM, Thymoglobulin (Thymo)) anti-lymphocyte Abs (ALAs) are used extensively in organ transplantation for immunosuppression induction, desensitization, and treatment of acute rejection. ALAs often interfere with post transplant immunologic monitoring. We describe a method that uses magnetic beads to selectively remove ALAs from patient serum. Rabbit anti-mouse Fc-specific (180 mug), or rabbit anti-mouse Fab-specific (180 microg), or rabbit anti-horse heavy and light chain-specific and rabbit anti-horse F(ab')2 (200 microg) (Jackson Immunoresearch) was adsorbed to 6.7 x 10(8) Dynabeads M-280 conjugated with sheep anti-rabbit IgG (Dynal Biotech). Fifty microliters of normal human serum (NHS) with 2 microg/ml of OKT3 or 100 microg/ml ATGAM, Thymo, or rituximab were incubated with conjugated beads for several incubations. NHS containing ALAs before and after treatment by the protocol were incubated with human lymphocytes and labeled with FITC-antibody to immunoglobulin of the species used to produce the particular ALA. Residual ALA was determined using flow cytometry. Average median channel for serum with or without ALA was 11.1 and 0.120, respectively for OKT3; 64.4 and 0.344 for ATGAM; 108.5 and 0.200 for Thymo; and 1022.5 and 11.4 for rituximab. Treatment lowered the median channel for serum with OKT3 to 0.103, 0.309 for ATGAM, 0.199 for Thymo, and 12.1 for rituximab. ALAs can be effectively removed from serum by the use of magnetic beads conjugated with Ab specific for ALA thereby permitting immunologic monitoring without interference.

Liver recipients harbouring anti-donor preformed lymphocytotoxic antibodies exhibit a poor allograft survival at the first year after transplantation: experience of one centre.

In this retrospective study, we analyzed the effect of the presence of anti-donor preformed alloantibodies in 268 liver allograft transplants. Crossmatches were performed by complement-dependent cytotoxicity (CDC) assay and HLA antibody screening by flow cytometry (FlowPRA). Positive anti-donor crossmatch was detected in 5.2% of transplants. Acute rejection frequency in +CDC crossmatch patients was not different from that observed in -CDC crossmatch patients. None of the patients transplanted with +CDC crossmatch developed chronic rejection, but they showed a significantly lower allograft survival rate, and the majority of them had allograft failures before the end of the first post-transplant year, mainly within the 3 first months. Indeed, positive FlowPRA determination was concordant with data from the CDC assay. In conclusion, these findings show a direct correlation between the presence of anti-donor preformed antibodies and a poor allograft survival in liver transplant.

Tg in Adults as a Sensitive Biomarker of Iodine Status: A 5-Year Follow up Population Study in Different Levels of Iodine Intake Regions.

This study was to evaluate the usefulness of serum thymoglobulin (Tg) in adults to assess iodine status through a 5-year cohort study which was conducted in three regions with different levels of iodine intake: mild deficiency, more than adequate, and excess, from 1999 to 2004 in China. A total of 3099 subjects over 14 years old with normal serum levels of Tg in 1999 were eligible, of whom 2448 were followed in 2004. Serum levels of thyroid hormones and thyroid autoantibodies as well as urine iodine were measured, and B-mode ultrasonography of the thyroid was performed. A general linear model was performed to determine the determinant factors of serum Tg. Among subjects with mildly deficient iodine intake, those with more than adequate intake, and those with excessive intake, the baseline levels of serum Tg were substantially different (7.5µg/L, 5.9µg/L, and 6.8µg/L respectively, P<0.01), which were associated with age, sex, the rate of positive TgAb, abnormal thyroid volume, abnormal TSH, and positive personal history of thyroid diseases. The data from 1856 subjects with normal range of thyroid parameters but no personal history of thyroid diseases were analyzed to clarify the effect of iodine intake on Tg. Among these three regions, the serum Tg levels were substantially different in both 1999 and 2004, with a similar pattern for increased Tg (ΔTg) (3.1µg/L, 2.5µg/L and 3.5µg/L respectively, P<0.01). The general linear model analysis revealed that age, Tg, and baseline TSH levels were the determinants of ΔTg besides iodine intake. In conclusion, serum Tg in adults, resulting from a time-accumulative effect of iodine exposure, is a useful biomarker of regional iodine intake.

Hepatitis C in renal transplant recipients.

Sera from 130 renal transplant recipients were tested for antibody to hepatitis C virus (anti-HCV). Anti-HCV was detected in 6.2% of patients: 15.4% of patients who had maintenance hemodialysis (HD) and 2.2% of those who had continuous ambulatory peritoneal dialysis (CAPD) before transplantation (P less than 0.05). The similarity in prevalence of anti-HCV with patients currently on dialysis and the absence of transfusion during posttransplant follow-up suggest that most patients acquired HCV infection through transfusion during dialysis. The proportion of anti-HCV-positive patients who had one or more episodes of elevation in serum transaminase level was similar to that of hepatitis B surface antigen (HBsAg)-positive patients, 75% vs. 72.2%. However, anti-HCV was only detected in 25% of HBsAg-negative patients who had recurrent elevations in serum transaminase level. It is not clear whether the low prevalence of anti-HCV in these patients is related to the presence of other non-A, non-B hepatitis virus (es) or a decrease in titer of anti-HCV secondary to immunosuppression posttransplantation.

Mechanism by which additional monoclonal antibody (mAB) injections overcome the requirement for thymic irradiation to achieve mixed chimerism in mice receiving bone marrow transplantation after conditioning with anti-T cell mABs and 3-Gy whole body irradiation.

A relatively nontoxic method of conditioning mice has been developed recently that allows allogeneic bone marrow engraftment and specific skin allograft tolerance induction. This regiment included anti-CD4 and anti-CD8 mAbs administered on day -5, followed by 3-Gy whole body irradiation (WBI) and 7-Gy thymic irradiation (TI) on day 0. We have recently shown that the potential toxicity of this regimen can be further reduced by replacing TI with additional anti-T cell mAb injections before and after bone marrow transplantation. Mixed chimerism and prolonged donor-specific skin graft acceptance are induced in 90% of B10 mice conditioned with anti-CD4 and anti-CD8 mAbs on days -6 and -1 and 3-Gy WBI on day 0 without TI, but only in a small fraction of mice receiving a similar regimen, except that mAbs are given on day -5 only. To determine the mechanism of tolerance induction in the former group, we compared the two groups for the extent of thymocyte depletion, for the timing of development of intrathymic and extrathymic chimerism, and for clonal deletion of host-type thymocytes with TCR recognizing superantigens presented by donor class II molecules. The results suggest that administration of a second mAb injection depletes or inactivates residual host thymocytes that are capable of causing intrathymic rejection of donor hematopoietic cells even when peripheral engraftment is achieved. The presence of donor class II+ hematopoietic cells in the thymus on day 14 correlated with marked deletion of mature host-type V beta 11+ thymocytes that recognize donor I-E plus endogenous superantigen. This suggests that tolerance is achieved primarily through a central deletional mechanism when peripheral and intrathymic host T cells are adequately inactivated or depleted by mAbs and 3-Gy WBI. In addition, the higher incidence of early failure of peripheral chimerism in mice conditioned with a single injection rather than than two mAb injections prior to bone marrow transplantation suggests that nontolerant residual host thymocytes can also induce early peripheral rejection after mAbs have cleared from the circulation. This early rejection is prevented by the longer persistence of anti-T cell mAbs observed in mice receiving two pretransplant mAb injections. Thus, administration of sufficient depleting anti-T cells mAbs followed by 3-Gy WBI allows the induction of central deletional tolerance while minimizing the toxicity of the conditioning regimen.