Initial experience of dual maintenance immunosuppression with steroid withdrawal in vascular composite tissue allotransplantation.

Current immunosuppression in VCA is largely based on the experience in solid organ transplantation. It remains unclear if steroids can be reduced safely in VCA recipients. We report on five VCA recipients who were weaned off maintenance steroids after a median of 2 months (mean: 4.8 months, range 2-12 months). Patients were kept subsequently on a low dose, dual maintenance consisting of tacrolimus and mycophenolate mofetil/mycophenloic acid with a mean follow-up of 43.6 months (median = 40 months, range 34-64 months). Early and late acute rejections responded well to temporarily augmented maintenance, topical immunosuppression, and/or steroid bolus treatment. One late steroid-resistant acute rejection required treatment with thymoglobulin. All patients have been gradually weaned off steroids subsequent to the treatment of acute rejections. Low levels of tacrolimus (<5 ng/mL) appeared as a risk for acute rejections. Although further experience and a cautious approach are warranted, dual-steroid free maintenance immunosuppression appears feasible in a series of five VCA recipients.

TIRC7 and HLA-DR axis contributes to inflammation in multiple sclerosis.

BACKGROUND AND OBJECTIVE: Interactions between TIRC7 (a novel seven-transmembrane receptor on activated lymphocytes) and its ligand HLA-DR might be involved in the inflammatory process in multiple sclerosis (MS). METHODS: Methods comprised immunohistochemistry and microscopy on archival MS autopsies, proliferation-, cytokine-, and surface-staining assays using peripheral blood lymphocytes (PBLs) from MS patients and an in vitro model. RESULTS: TIRC7 was expressed in brain-infiltrating lymphocytes and strongly correlated with disease activity in MS. TIRC7 expression was reduced in T cells and induced in B cells in PBLs obtained from MS patients. After ex vivo activation, T cell expression of TIRC7 was restored in patients with active MS disease. The interaction of TIRC7(+) T lymphocytes with cells expressing HLA-DR on their surface led to T cell proliferation and activation whereas an anti-TIRC7 mAb preventing interactions with its ligand inhibited proliferation and Th1 and Th17 cytokine expression in T cells obtained from MS patients and in myelin basic protein-specific T cell clone. CONCLUSION: Our findings suggest that TIRC7 is involved in inflammation in MS and anti-TIRC7 mAb can prevent immune activation via selective inhibition of Th1- and Th17-associated cytokine expression. This targeting approach may become a novel treatment option for MS.

Detecting antibodies with similar reactivity patterns in the HLDA8 blind panel of flow cytometry data.

The blind panel collected for the 8th Human Leucocyte Differentiation Antigens Workshop (HLDA8; ) included 49 antibodies of known CD specificities and 76 antibodies of unknown specificity. We have identified groups of antibodies showing similar patterns of reactivity that need to be investigated by biochemical methods to evaluate whether the antibodies within these groups are reacting with the same molecule. Our approach to data analysis was based on the work of Salganik et al. (in press) [Salganik, M.P., Milford E.L., Hardie D.L., Shaw, S., Wand, M.P., in press. Classifying antibodies using flow cytometry data: class prediction and class discovery. Biometrical Journal].

Classifying antibodies using flow cytometry data: class prediction and class discovery.

Classifying monoclonal antibodies, based on the similarity of their binding to the proteins (antigens) on the surface of blood cells, is essential for progress in immunology, hematology and clinical medicine. The collaborative efforts of researchers from many countries have led to the classification of thousands of antibodies into 247 clusters of differentiation (CD). Classification is based on flow cytometry and biochemical data. In preliminary classifications of antibodies based on flow cytometry data, the object requiring classification (an antibody) is described by a set of random samples from unknown densities of fluorescence intensity. An individual sample is collected in the experiment, where a population of cells of a certain type is stained by the identical fluorescently marked replicates of the antibody of interest. Samples are collected for multiple cell types. The classification problems of interest include identifying new CDs (class discovery or unsupervised learning) and assigning new antibodies to the known CD clusters (class prediction or supervised learning). These problems have attracted limited attention from statisticians. We recommend a novel approach to the classification process in which a computer algorithm suggests to the analyst the subset of the "most appropriate" classifications of an antibody in class prediction problems or the "most similar" pairs/ groups of antibodies in class discovery problems. The suggested algorithm speeds up the analysis of a flow cytometry data by a factor 10-20. This allows the analyst to focus on the interpretation of the automatically suggested preliminary classification solutions and on planning the subsequent biochemical experiments.

Soluble HLA-II expression in African-Americans.

OBJECTIVE: In this study we evaluated the contribution of major histocompatibility complex (MHC) genes to soluble histocompatibility antigen class II (sHLA-II) secretion in African American patients with rheumatoid arthritis (RA). METHODS: A sensitive enzyme-linked immunoassay was used to quantitate sHLA-II in the serum of 7 patients with RA, as well as 28 of their kinships and 49 HLA typed normal African American individuals. RESULTS: Mean sHLA-II values were higher in patients with RA than those in healthy African American individuals (p < 0.05). There were variations in concentrations in individual patients but these were unrelated to any apparent clinical event. The proportion of unaffected family members with detectable levels of sHLA-II was not significantly different than those in normal controls. Neither specific HLA-haplotype, or HLA-allele(s) correlated with high or low sHLA-II secretion. CONCLUSIONS: Our data suggest that sHLA-II molecules are not regulated by MHC linked genes but may be regulated by non-MHC linked genes and racial background may reflect genetic heterogeneity of the expression of this soluble HLA material. These observations contrast with previous observations concerning soluble HLA class I (sHLA-I) molecules in a described population sample which were almost the precise reverse.

Angiotensin gene polymorphism as a determinant of posttransplantation renal dysfunction and hypertension.

BACKGROUND: Polymorphism of the genes associated with angiotensin, including angiotensin-converting enzyme (ACE), angiotensinogen (AGT), and the type 1 (AT1) and type 2 (AT2) angiotensin II receptors, has been implicated in the pathophysiology of hypertension, ischemic heart disease, and progression of chronic renal disease. METHODS: We investigated the impact of the ACE, AGT, AT1, and AT2 genotypes on renal allograft function in 148 patients (77 men, 71 women) who underwent transplantation over a 5-year period. Patients were genotyped using polymerase chain reaction sequence-specific primers and polymerase chain reaction followed by restriction fragment length polymorphism analysis. RESULTS: ACE (D) and AGT (A/A) genotypes were associated with poorer chronic renal transplant function and more rapid chronic progression, defined as an increase of serum creatinine level with time. In addition, mean diastolic blood pressure at 3 years was significantly (P<0.02) correlated with C gene dose of AT1 (A-->C, 1166), with levels of 79+/-10 mmHg, 82+/-8.6 mmHg, and 95+/-8.3 mmHg for the A/A, A/C, and C/C genotypes, respectively. An apparent AT2 homozygote disadvantage could be an epiphenomenon because AT2 maps to the X chromosome, and males are homozygous for just one of the AT2 alleles (A/- or G/-). CONCLUSIONS: Pretransplantation testing of the ACE, AGT, and AT1 genotypes may assist clinicians in identifying patients at risk for chronic renal transplant dysfunction and hypertension.

Molecular identification using flow cytometry histograms and information theory.

Flow cytometry is a common technique for quantitatively measuring the expression of individual molecules on cells. The molecular expression is represented by a frequency histogram of fluorescence intensity. For flow cytometry to be used as a knowledge discovery tool to identify unknown molecules, histogram comparison is a major limitation. Many traditional comparison methods do not provide adequate assessment of histogram similarity and molecular relatedness. We have explored a new approach applying information theory to histogram comparison, and tested it with histograms from 14 antibodies over 3 cell types. The information theory approach was able to improve over traditional methods by recognizing various non-random correlations between histograms in addition to similarity and providing a quantitative assessment of similarity beyond hypothesis testing of identity.

A compendium of gene expression in normal human tissues.

This study creates a compendium of gene expression in normal human tissues suitable as a reference for defining basic organ systems biology. Using oligonucleotide microarrays, we analyze 59 samples representing 19 distinct tissue types. Of approximately 7,000 genes analyzed, 451 genes are expressed in all tissue types and designated as housekeeping genes. These genes display significant variation in expression levels among tissues and are sufficient for discerning tissue-specific expression signatures, indicative of fundamental differences in biochemical processes. In addition, subsets of tissue-selective genes are identified that define key biological processes characterizing each organ. This compendium highlights similarities and differences among organ systems and different individuals and also provides a publicly available resource (Human Gene Expression Index, the HuGE Index, http://www.hugeindex.org) for future studies of pathophysiology.

Differences in access to cadaveric renal transplantation in the United States.

This national study compares waitlisting and transplantation rates by gender, race, and diabetes and evaluates physiologic factors (panel-reactive antibodies [PRA], blood type, HLA matchability) and related practices (early and multiple waitlisting) as explanatory factors. This longitudinal study of the time to transplant waitlisting among 228,552 incident end-stage renal disease (ESRD) dialysis patients and to cadaveric transplantation among 46,164 waitlist dialysis patients (n = 23,275 first cadaveric transplants) used US data for 1991 to 1997. Relative rates of waitlisting (RRWL) after ESRD onset and of cadaveric transplantation (RRTx) after waitlist (Cox proportional hazards models) were adjusted for age, race, sex, ESRD cause, region, and incidence/waitlist year. We found that women have an RRWL = 0.84 (P < 0.0001) and RRTx = 0.86 (P < 0. 0001). PRA levels can explain the difference in the transplantation rate, because accounting for PRA gives an adjusted RRTx = 0.98 (NS) for women. For blacks versus whites, the RRWL = 0.59 (P < 0.0001) and RRTx = 0.55 (P < 0.0001). However, the transplantation rate can only partly be explained by ABO types, rare HLA types, and early and multiple waitlisting (adjusted RRTx = 0.67 [P < 0.0001]). For diabetes versus glomerulonephritis, the RRWL = 0.52 (P < 0.0001) and RRTx = 0.98 (NS). Older patients (40 to 59 years of age) are less likely to be waitlisted and to receive a transplant after waitlisting (RRWL = 0.57 [P < 0.0001], RRTx = 0.88 [P < 0.0001]) versus younger patients (ages 18 to 39 years). These results indicate substantial differences by age, sex, race, and diabetes in rates of waitlisting for transplantation and by age and race for transplantation after waitlisting. These differences by race were not explained by referral practices or the physiologic factors studied here.

Probability of finding HLA-mismatched related or unrelated marrow or cord blood donors.

Given recent improvements in the technology of transplantation and histocompatibility testing, it is now possible to contemplate using related or unrelated allogeneic hematologic stem cell donors with high degrees of HLA disparity. This paper is a follow-up of an earlier publication on the probability of finding a matched donor (Transplantation 60:778-783, 1995) and addresses the probability of finding a partially mismatched donor. Assuming that a four of six antigen HLA-A, -B, -DR match is acceptable, it is possible to find unrelated donors for patients of any race from a putative registry with fewer than 10,000 potential donors. Further, storing cord blood from newborns in families with a known genetic disease would yield an acceptable future stem cell transplant product in nearly 40% of cases. These results show the potential impact of cord blood donors and emphasize the importance of improvements in transplantation using partially mismatched donors.

Accelerated rejection of renal allografts from brain-dead donors.

OBJECTIVE: To define the potential influences of donor brain death on organs used for transplantation. SUMMARY BACKGROUND DATA: Donor brain death causes prompt upregulation of inflammatory mediators on peripheral organs. It is hypothesized that this antigen-independent insult may influence the rate and intensity of host alloresponsiveness after engraftment. METHODS: The rates of survival of unmodified Lew recipients sustained by kidney allografts from brain-dead, normal anesthetized, and anesthetized ventilated F344 donors were compared. Brain death was induced by gradually increasing intracranial pressure under electroencephalographic control. Tracheotomized brain-dead animals and anesthetized controls were mechanically ventilated for 6 hours before transplant nephrectomy. The rate and intensity of the acute rejection event were examined by histology, immunohistology, and reverse transcriptase-polymerase chain reaction. RESULTS: Animals bearing kidneys from brain-dead donors died of renal failure secondary to acute rejection at a significantly faster rate than those from anesthetized living controls or anesthetized animals ventilated for 6 hours. Within 3 hours after placement and reperfusion of brain-dead donor grafts, significant neutrophil infiltration was observed, followed by increasing numbers of macrophages and T cells. mRNA of proinflammatory mediators detected in kidneys within 6 hours of brain death and upregulated even before transplantation increased thereafter and appeared to accelerate and amplify host alloresponsiveness, as manifested by the rapid expression of chemokines, cytokines, adhesion molecules, and major histocompatibility complex class II antigens in the engrafted organ. The process evolved in the controls less intensely and at a slower rate. CONCLUSIONS: Donor brain death is a significant risk factor for peripheral organs used for transplantation. The activated state of such organs appears to trigger host immune mechanisms that accelerate the process of acute rejection. The effects of this central injury may explain in part the less satisfactory performance of cadaver organs in human transplantation compared with those from living sources.

Comparison of mortality in all patients on dialysis, patients on dialysis awaiting transplantation, and recipients of a first cadaveric transplant.

BACKGROUND AND METHODS: The extent to which renal allotransplantation - as compared with long-term dialysis - improves survival among patients with end-stage renal disease is controversial, because those selected for transplantation may have a lower base-line risk of death. In an attempt to distinguish the effects of patient selection from those of transplantation itself, we conducted a longitudinal study of mortality in 228,552 patients who were receiving long-term dialysis for end-stage renal disease. Of these patients, 46,164 were placed on a waiting list for transplantation, 23,275 of whom received a first cadaveric transplant between 1991 and 1997. The relative risk of death and survival were assessed with time-dependent nonproportional-hazards analysis, with adjustment for age, race, sex, cause of end-stage renal disease, geographic region, time from first treatment for end-stage renal disease to placement on the waiting list, and year of initial placement on the list. RESULTS: Among the various subgroups, the standardized mortality ratio for the patients on dialysis who were awaiting transplantation (annual death rate, 6.3 per 100 patient-years) was 38 to 58 percent lower than that for all patients on dialysis (annual death rate, 16.1 per 100 patient-years). The relative risk of death during the first 2 weeks after transplantation was 2.8 times as high as that for patients on dialysis who had equal lengths of follow-up since placement on the waiting list, but at 18 months the risk was much lower (relative risk, 0.32; 95 percent confidence interval, 0.30 to 0.35; P<0.001). The likelihood of survival became equal in the two groups within 5 to 673 days after transplantation in all the subgroups of patients we examined. The long-term mortality rate was 48 to 82 percent lower among transplant recipients (annual death rate, 3.8 per 100 patient-years) than patients on the waiting list, with relatively larger benefits among patients who were 20 to 39 years old, white patients, and younger patients with diabetes. CONCLUSIONS: Among patients with end-stage renal disease, healthier patients are placed on the waiting list for transplantation, and long-term survival is better among those on the waiting list who eventually undergo transplantation.

Early experience with dual kidney transplantation in adults using expanded donor criteria. Double Kidney Transplant Group (DKG).

Dual transplant of marginal kidneys otherwise not considered for single transplant may give access to an expanded pool of cadaveric organs without exposing recipients to the drawbacks of a limited nephron mass supply. This prospective, case-control study compares adverse events and graft outcome in 24 recipients of two marginal kidneys from donors who were >60 yr old or who had diabetes, hypertension, or non-nephrotic proteinuria (cases), with that of 48 age- and gender-matched control subjects who received single ideal grafts at the same center and were given the same immunosuppressive therapy. Marginal kidneys with no macroscopic abnormalities were selected for the double transplant on the basis of a predefined score of histologic damage. Six-month patient and kidney survival was 100% with both of the procedures. Incidence (20.8% versus 20.8%) and median (range) duration of posttransplant anuria (5 [2 to 12] versus 7 [2 to 13] days) were comparable in cases and control subjects, respectively. Time to normal serum creatinine and mean serum creatinine values at each time visit were comparable as well, but with significantly lower levels in cases compared with control subjects from month 2 to last follow-up (1.56 +/- 0.65 versus 1.74 +/- 0.73 mg/dl, P = 0.04). Diastolic BP values averaged during the entire posttransplant period were significantly lower in cases than in control subjects (83.2 +/- 11.5 versus 85.1 +/- 12.5 mmHg, respectively, P = 0.008). Donor/recipient body weight ratio was the only covariate significantly associated at univariate (P = 0.002) and multivariate (P = 0.001) analysis with last available serum creatinine concentrations. Incidence of acute allograft rejections (20.8% versus 18.8%) and of major surgical complications was comparable in the two groups. No renal artery or vein thrombosis was reported in either group. Dual transplants of marginal kidneys are as safe and tolerated as single transplants, and possibly offer an improved filtration power without exposing the recipient to enhanced risk of delayed renal function recovery, acute allograft rejection, or major surgical complications.

Nocardial infection in a renal transplant recipient on tacrolimus and mycophenolate mofetil.

Infection with Nocardia spp. is an uncommon but important cause of morbidity and mortality in organ transplant recipients. Cotrimoxazole prophylaxis against urinary tract infection and Pneumocystis carinii pneumonia in these patients usually prevents nocardial infection also. We report the case of a patient on tacrolimus and mycophenolate mofetil who developed drug-induced diabetes mellitus followed by nocardial brain infection. This infection occurred despite conventional cotrimoxazole prophylaxis. Physicians should be aware that newer, more potent and more diabetogenic immunosuppressive regimens may increase the risk of opportunistic infections such as nocardiosis, even in the presence of "adequate" antimicrobial preventive measures.

The pathology of transfusion-related acute lung injury.

Transfusion-related acute lung injury is an uncommon condition characterized by the rapid onset of respiratory distress soon after transfusion. Our understanding of its pathophysiology is based on animal models of complement (C5a) and antibody-induced lung injury and a limited number of autopsies. These models suggest that transfusion-related acute lung injury is induced by granulocytes that aggregate in the pulmonary microvasculature after activation by transfusion-derived antibodies or biologically active lipids. The published autopsy reports provide little support for this model, as they are invariably confounded by underlying pulmonary infection, preexisting disease, and resuscitation injury. We report the case of a previously well 58-year-old man who died of transfusion-related acute lung injury within 2 hours of the onset of pulmonary distress; autopsy showed evidence of massive pulmonary edema with granulocyte aggregation within the pulmonary microvasculature and extravasation into alveoli. Electron microscopy revealed capillary endothelial damage with activated granulocytes in contact with the alveolar basement membranes. These findings provide direct support for the proposed model of transfusion-related acute lung injury pathogenesis.

Immunosuppressive agents in organ transplantation.

This article reviews current and future immunosuppressive strategies in organ transplantation. Recently introduced drugs are lowering the rates of acute rejection and allowing more individualized management of transplanted patients.

A new allocation plan for renal transplantation.

BACKGROUND: A novel plan of renal allograft allocation has been conducted by United Network for Organ Sharing Region 1 transplant centers since September 3, 1996, based upon HLA matching, time waiting, and population distance points. The objectives of this plan were to achieve a balance between increasing the opportunity of renal transplantation for those patients listed with long waiting times and promoting local organ donor availability. METHODS: A single list of candidates was formulated for each cadaver donor, assigning a maximum of 8 points for time waiting, a maximum of 8 points for population distance from the donor hospital, and HLA points based upon the degree of B/DR mismatch. Additional points were awarded to a cross-match-negative patient with a panel-reactive antibody of >80%, and to pediatric patients. RESULTS: The total number of kidneys transplanted to patients who had waited >3 years was 100 (46%), and to patients who had waited >2.5-3 years was 29 (13%). However, the total number of kidneys transplanted to patients with the maximum population distance points was only 72 (33%). Thus, although the plan achieved a favorable distribution of kidneys to patients with longer waiting times (nearly 60%), the other, equally important objective of promoting local donor availability was not initially accomplished. Moreover, minor HLA B/DR differences between the donor and the recipient (i.e., not phenotypically matched) were unexpectedly consequential in determining allocation. As a result of these observations, the following adjustments were made in the plan (as of December 3, 1997): a maximum of 10 points for population distance, a maximum of 8 points for time waiting (both by a linear correlation), and the retention of HLA points for 0 B/DR mismatch only. After these interval changes, the percentage of patients receiving a kidney with some population distance points increased from 85% to 96%. Conclusions. We have shown that a heterogeneous region of multiple transplant centers can devise (and modify) an innovative and balanced plan that provides an equitable system of allocation for an ever-increasing number of patients.

A novel united network for organ sharing region kidney allocation plan improves transplant access for minority candidates.

BACKGROUND: We report the consequences of a novel kidney allocation system on access of non-Caucasians (NC) to kidney transplantation. This new plan has provided a balance of allocation determinants between time waiting, HLA match, and geography (population density between donor and recipient center). METHODS: Three sequential systems of regional allocation were analyzed: period I (September 1994 to September 1996), period II (September 1996 to November 1997), and period III (December 1997 to March 1 1999). Periods II and III are reflective of the new allocation plan. RESULTS: During periods II and III, the NC rate of kidney transplantation increased closer to the NC proportion on the wait list, comparatively exceeding the national UNOS data. There was no statistical difference in regional mean wait time between Caucasian and NC. Improvements in access to transplantation for NCs between period I and periods II and III appear to be related to changes in geographic allocation weight from local unit to population density points, to the inclusion of the entire region in the plan, and to the deletion of intermediate degrees of B/DR mismatching in the revised plan. Despite the increased proportion of NCs on the wait list from period I to period III, the percentage difference between the proportion of NCs waiting on the list and the proportion NCs receiving a transplant fell from 7.8% to 4.9%. CONCLUSIONS: These data demonstrate that this new allocation plan was associated with improved access of minority candidates to transplantation. The broadening of geographic allocation and the alteration of HLA points appear to permit a more favorable opportunity for renal transplantation to NC candidates. selection, compared to the UNOS formula. In this report, we analyze the consequences of the Region 1 allocation system on the access of non-Caucasian (NC) candidates to cadaver donor kidney transplantation.

Prevention of acute allograft rejection by antibody targeting of TIRC7, a novel T cell membrane protein.

A novel 75 kDa membrane protein, TIRC7, is described that exhibits a central role in T cell activation in vitro and in vivo. Modulation of TIRC7-mediated signals with specific anti-TIRC7 antibodies in vitro efficiently prevents human T cell proliferation and IL-2 secretion. Moreover, anti-TIRC7 antibodies specifically inhibit type 1 subset specific IFN-gamma expression but spare the type 2 cytokine IL-4. Diminished proliferation but not IFN-gamma secretion is reversible by exogenous rIL-2. An anti-TIRC7 antibody that cross-reacts with the 75 kDa rat homolog exhibits inhibition of rat alloimmune response in vitro and significantly prolongs kidney allograft survival in vivo. Targeting of TIRC7 may provide a novel therapeutic approach for modulation of the immune response.