Kevin M. Rosner

Analysis of anti-HLA antibodies in sensitized kidney transplant candidates subjected to desensitization with intravenous immunoglobulin and rituximab.

Background Preexisting donor-specific antibodies against human leukocyte antigens are major risk factors for acute antibody-mediated and chronic rejection of kidney transplant grafts. Immunomodulation (desensitization) protocols may reduce antibody concentration and improve the success of transplant. We investigated the effect of desensitization with intravenous immunoglobulin and rituximab on the antibody profile in highly sensitized kidney transplant candidates. Methods In 31 transplant candidates (calculated panel-reactive antibody [cPRA], 34%–99%), desensitization included intravenous immunoglobulin on days 0 and 30 and a single dose of rituximab on day 15. Anti–human leukocyte antigen antibodies were analyzed before and after desensitization. Results Reduction of cPRA from 25% to 50% was noted for anti–class I (5 patients, within 20–60 days) and anti–class II (3 patients, within 10–20 days) antibodies. After initial reduction of cPRA, the cPRA increased within 120 days. In 24 patients, decrease in mean fluorescence intensity of antibodies by more than 50% was noted at follow-up, but there was no reduction of cPRA. Rebound occurred in 65% patients for anti–class I antibodies at 350 days and anti–class II antibodies at 101 to 200 days. Probability of rebound effect was higher in patients with mean fluorescence intensity of more than 10,700 before desensitization, anti–class II antibodies, and history of previous transplant. Conclusions The desensitization protocol had limited efficacy in highly sensitized kidney transplant candidate because of the short period with antibody reduction and high frequency of rebound effect.

Subtypes of immunoglobulin (Ig)-G antibodies against donor class II HLA and cross-match results in three kidney transplant candidates

Preexisting donor-specific antibodies (DSA) play a critical role in the success of solid-organ transplantation. Cross-match (CM) between donor lymphocytes and recipient serum is a pivotal methodology for detecting these antibodies. Luminex platform based solid-phase methodology for anti-human leukocyte antigen (HLA) antibody analysis has revolutionized the approach to antibody detection and HLA specificity identification. In this study, we have reported three cases of successful living donor kidney transplantations performed against strongly positive B lymphocyte flow cytometry (FC) CM owing to highly reactive DSA directed to HLA class II. IgG solid-phase subtype analysis showed that more than 50% of these antibodies were represented by non-complement binding IgG2/IgG4 subtypes. These findings account for antibody mediated rejection (AMR) free long-term post-transplant course in these patients despite, the high level of DSA. Thus, we conclude that routine application of single HLA-coated beads (SAB) IgG subtype assay may provide new insights regarding transplantation or desensitization of patients presenting with negative B-cell complement dependent cytotoxic (CDC) and positive FC CM.

Immunogenicity of Class I HLA but not preformed low MFI donor specific antibodies correlates with outcomes after first renal transplantation

BACKGROUND The role of low levels of circulating donor specific antibodies (DSA) producing negative flow cytometry cross match is not completely defined. The purpose of this study was to examine the clinical significance of preexisting low levels of class I DSAs in flow cytometry cross match (FC CM) negative first kidney transplant recipients (KTRs). METHODS All of the KTRs (n=41) had low levels of anti-class I antibodies only. The kidney transplant outcome was evaluated by the development of a deleterious effect (DE) in recipients in the study cohort (Group 1: DE+, Group 2: DE-). Positivity for DE was determined based on the following criteria: biopsy proven transplant glomerulopathy (TG), de novo development of DSAs, increasing MFI values for preexisting DSAs, and the development of biopsy proven AMR. Anti-HLA antibodies were tested using single antigen Luminex technology. The HLAMatchmaker computer algorithm was used for the immunogenicity analysis of antibody verified (AbVer) mismatched eplets (MME) at the HLA-A and B loci. RESULTS The results of this study showed that the number of AbVer MME is larger (P=0.03) in the group of KTR who developed DE. We also demonstrated that the number of AbVer MME is a strong predictor of post-transplant DE. These results indicate that persistent weakly reactive DSA is not a significant risk factor for the development of post-transplant DE and that recipients with such antibodies can be successfully transplanted. CONCLUSIONS Immunogenicity of AbVer MME at HLA-A and B loci is strong predictor of post-transplant increases of the MFI values of preexisting or de novo developed DSA in the FC CM negative first KTR. Avoiding of transplants with more than eleven Class I AbVer MMEs may be the optimal approach to reduce the risk of kidney graft failure.

Rapid and strong de novo donor-specific antibody development in a lung transplant recipient: Short communication/case report

A 66-yo female patient (typed B*39:01, 44:02) underwent first left single lung transplant (typed B*81:01, 15:17) on 02/07/2016 with negative for DSA in current and historical samples. On 02/17/2016 strong de novo DSA (MFI=15,200, C1q+) to B81 were detected. The recipient has two children typed B*07:02, 44:02 B*27:03, 39:01, and had received multiple vaccinations. Twinrix, Zostavax and MMR vaccines contain viruses grown on live human lung fibroblasts (MRC-5, typed B*07:02, 44:02, and WI-38, typed B*08:01, 58:01). Each dose of vaccine used for injection is known to contain protein components of fibroblasts including HLA. Most likely rapid de novo DSA development is due to booster effect produced by five exposures to mismatched B locus alleles which share the following epitopes: 70IAQ, 65QIA, 65QIA+76esn, 69aa+80n, and 163ew+73te. The later three consist of paired non-self and self eplets. Although likelihood of bystander effect produced by multiple vaccinations is low its impact cannot be ruled out.