Shared Molecular Eplet Stimulates Acute Antibody-Mediated Rejection in a Kidney Transplant Recipient With Low-Level Donor-Specific Antibodies: A Case Report

HLA antibodies usually recognize epitopes rather than antigens. This case report reveals that acute antibody-mediated rejection (AMR) that occurred in a kidney transplant recipient with low-level donor-specific antibodies (DSAs) could be explained by shared epitope. A 39-year-old woman received a first kidney transplant from a deceased donor (HLA-DRB1*11:06, *12:02, DRB3*02:02, *03:01). She developed acute AMR confirmed by kidney biopsy on day 4 after transplantation. Antibody testing with pretransplant serum showed anti-DR11 DSA below cutoff level (mean fluorescence intensity [MFI], 702; cutoff >1,000). However, high-level DSAs were detected on day 5 after transplantation (anti-DR11 MFI, 8,531; anti-DR12 MFI, 3,146). We hypothesized that the sharp rise in DSA levels was a result of anamnestic response with donor-antigen sensitization that occurred during pregnancy. High-resolution HLA-DR typing of her husband showed HLA-DRB1*03:01, *15:02:01, DRB3*02:02, DRB5*01:02. No sharing between donor HLAs eliciting reactive antibodies and her husband's HLAs was detected. Nevertheless, we speculated that shared epitope, not antigen, was the cause of allosensitization. To identify the shared epitope recognized by patient's antibodies, we used HLAmatchmaker, a computer algorithm that considers small configurations of polymorphic residues referred to as eplets as essential components of HLA epitopes for analysis. The results showed that 149H, which was the eplet shared by HLA-DRB1*03:01 (from her husband) and DRB1*11:06, DRB1*12:02, DRB3*03:01 (from donor), was the most prevalent eplet on DRB1 reactive alleles in Luminex assay. In conclusion, pretransplant low-level DSAs can induce AMR early after transplantation as a result of shared epitopes with a previous immunizer.     

Cytotoxic flow cytometric crossmatch in renal transplantation: a single assay to simultaneously detect antibody binding and cytotoxicity

Objectives

The complement-dependent lymphocytotoxicity crossmatch (CDC-XM) detects cytotoxic parameters of preformed antibodies. The flow cytometric crossmatch (FCXM) is used to detect the binding of recipient antibodies to donor cells. Because these two assays provide different information, both methods are often performed to assess the compatibility of donor-recipient pairs. The aim of this study was to develop a single assay that can simultaneously detect antibody binding and cytotoxicity.

Methods

A procedure called cytotoxic flow cytometric crossmatch (cFCXM) that determines cell death and antibody binding simultaneously was developed. The assay was validated in parallel with extended incubation CDC-XM. Receiver operating characteristic analysis was used to determine the cut-off level. Furthermore, pretransplantation sera from seven recipients with pretransplantation donor-specific antibodies (DSA) and negative CDC-XM were retrospectively tested for cFCXM (4 without antibody-mediated rejection (AMR) and three with AMR).

Results

The optimal method for the simultaneous detection of antibody binding and cytotoxicity in a single assay has been determined. Four of four patients (100%) with pretransplantation DSA and without AMR had negative cFCXM in both parameters. Of three patients with pretransplantation DSA who developed AMR, two patients (66.7%) had positive B-cell cFCXM in both parameters, and 1 patient (33.3%) had positive T-cell cFCXM in a binding parameter only. The first patient had anti-DR9, DR53, DQ9, the second patient had anti-A11, DR12 and the last one had an anti-B46 in their pretransplantation sera. These 3 cases experienced biopsy-proven AMR after living-donor kidney transplantation.

Conclusion

The newly developed assay, cFCXM, can simultaneously determine cytoxicity and antibody binding using a single platform. Furthermore, this assay can detect clinically significant HLA alloantibodies undetectable by conventional crossmatches. The cFCXM could serve as a new tool for the detection of a recipient's alloantibodies.     

Croblongifolin, a new anticancer clerodane from Croton oblongifolius

A new furoclerodane, croblongifolin, together with one known clerodane, crovatin and one known labdane, nidorellol, were isolated from the stem bark of Croton oblongifolius. Structures were established based on spectroscopic and X-ray analysis. Croblongifolin showed a significant cytotoxicity against various human tumor cell lines including HEP-G2, SW620, CHAGO, KATO3 and BT474.     

The role of anti-IL-2 receptor in high-risk kidney transplant patients

Anti-IL-2 receptor has been proved to be effective in reducing the rate of acute rejection in kidney transplantation and also improving both the rate of graft and patient survival. In this study, we retrospectively review the role of anti-IL-2 receptor as induction immunosuppression in immunologically high-risk kidney transplant patient compared with normally low-risk patients. METHODS: From January 1999 to December 2002, we performed 246 kidney transplantations in two transplant centers in Bangkok. These were divided into two groups: group 1, high-risk group containing 50 patients who had one of the following criteria: (1) high panel reactive antibody (>50%); (2) retransplantation; (3) marginal donor (with expectancy of delayed graft function); (4) spouse donor; (5) >4 HLA mismatch. All group 1 patients receive anti-IL-2 receptor as induction immunosuppression (either Basiliximab (n = 27) or Daclizumab (n = 23).) Group 2 consisted of the control group of 196 patients with normal immunological risk. The following data of both groups were collected and analyzed: patient demography, type of donor, acute rejection incidence, severity, and time. RESULTS: In this study, the anti-IL-2 receptors are 27 cases of Basiliximab and 23 cases of Daclizumab. The rates of acute rejection are not significantly different in both groups, namely, 46 of 194 (23.7%) in group 2 compared with 10 of 50 (20%) episodes in group 1 (P = .602). All rejections in both groups responded to pulse steroid treatment. The mortality rate and rate of graft failure were also not significantly different, i.e., 6 of 196 (3.1%) vs 2 of 50 (4.0%) (P = .666) and 7 of 196 (3.6%) vs 3 of 50 (6.0%) (P = .429) in low risk group versus high risk group, respectively. Kaplan-Meier estimates of the probabilities of acute rejection free, patient survival rate, and graft survival rate also showed no difference between groups. CONCLUSIONS: The use of anti-IL-2 receptor antibodies as induction immunosuppression in immunologically high-risk patients results in the same rate of acute rejection, severity of acute rejection, graft survival, and patient survival as recipients with normal immunological risk.     

Treatment of Simultaneous Acute Antibody-Mediated Rejection and Acute Cellular Rejection With Alemtuzumab in Kidney Transplantation: A Case Report

This is a case report of a living related donor kidney transplantation using basiliximab induction and maintenance immunosuppression with cyclosporine, mycophenolate sodium, and steroid. On the second posttransplant day, the patient developed acute antibody-mediated rejection, which was treated with plasmapheresis and intravenous immunoglobulin (IVIG). Five days later, the graft had still not responded to the treatment. Another biopsy revealed additional acute cellular rejection (Banff IIA). As alemtuzumab can rapidly deplete T and B lymphocytes, monocytes, and natural killer cells, the patient was treated with alemtuzumab (30 mg subcutaneously) together with methylprednisolone (500 mg) and two more plasmaphereses. The kidney graft responded within 48 hours, producing more than 4 L of urine per day. The total lymphocyte decreased from 530/μL to 50/μL remaining in the 50 to 220/μL range. The patient received valgancyclovir and cotrimoxazole as infection prophylaxis. The kidney graft responded well to the rescue treatment and the patient was discharged with a serum creatinine of 1.1 mg/mL and has been uneventfully followed in the outpatient clinic for 8 months. Today, with the potent, effective, and selective immunosuppressive regimens, the rate and severity of acute cellular rejection in kidney transplantation has decreased in most centers. However, the rate of acute antibody-mediated rejection has increased to levels greater than those of acute cellular rejection in many centers. Acute antibody-mediated rejection is more difficult and expensive to treat successfully. The treatment of acute antibody-mediated rejection included plasmapheresis and IVIG. Herein we have reported a case of kidney transplantation simultaneously developing acute antibody-mediated and acute cellular rejection; the patient was successfully treated with alemtuzumab.     

Outcomes of Direct Pulp Capping by Using Either ProRoot Mineral Trioxide Aggregate or Biodentine in Permanent Teeth with Carious Pulp Exposure in 6- to 18-Year-Old Patients: A Randomized Controlled Trial

Introduction

This study aimed to compare the success rates of direct pulp capping (DPC) by using either ProRoot Mineral Trioxide Aggregate (MTA) or Biodentine in the cariously exposed permanent teeth of 6- to 18-year-old patients. Gray discoloration was also evaluated.

Cytotoxic activity of natural labdanes and their semi-synthetic modified derivatives from Croton oblongifolius

Labda-7,12( E),14-triene-17-oic acid, previously isolated from Croton oblongifolius, and its derivatives were investigated for cytotoxicity against five human tumor cell lines. Six of these compounds, labda-7,12( E),14-triene-17-al, 17-hydroxylabda-7,12( E),14-triene, 17-acetoxylabda-7,12( E),14-triene, 15-hydroxylabda-7,13( E)-diene-17,12-olide, labda-7,13( E)-diene-17,12-olide, and 12,17-dihydroxylabda-7,13( E)-diene showed non-specific, moderate, cytotoxicity against all cell lines, whereas the other compounds were inactive.