Pretransplant HLA typing revealed loss of heterozygosity in the major histocompatibility complex in a patient with acute myeloid leukemia.

INTRODUCTION: Chromosomal abnormalities are frequent events in hematological malignancies. The degree of HLA compatibility between donor and recipient in hematopoietic stem cell transplantation is critical. PURPOSE OF THE STUDY: In this report, we describe an acute myeloid leukemia case with loss of heterozygosity (LOH) encompassing the entire HLA. MATERIALS AND METHODS: HLA molecular typing was performed on peripheral blood (PB) and buccal swabs (BS). Chromosomal microarray analysis (CMA) was performed using a whole genome platform. RESULTS: Typing results on PB sample collected during blast crisis demonstrated homozygosity at the -A, -B, -C, -DR, and -DQ loci. A BS sample demonstrated heterozygosity at all loci. A subsequent PB sample drawn after count recovery confirmed heterozygosity. The CMA performed on PB samples collected during and after blast crisis revealed a large terminal region of copy-neutral LOH involving chromosome region 6p25.3p21.31, spanning approximately 35.9 Mb. The results of the CMA assay on sample collected after count recovery did not demonstrate LOH. CONCLUSIONS: LOH at the HLA gene locus may significantly influence the donor search resulting in mistakenly choosing homozygous donors. We recommend confirming the HLA typing of recipients with hematological malignancies when homozygosity is detected at any locus by using BS samples, or alternatively from PB when remission is achieved.

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.

Methodological aspects of anti-human leukocyte antigen antibody analysis in solid organ transplantation.

Donor human leukocyte antigen (HLA)-specific antibodies (DSA) play an important role in solid organ transplantation. Preexisting IgG isotype DSA are considered a risk factor for antibody mediated rejection, graft failure or graft loss. The post-transplant development of DSA depends on multiple factors including immunogenicity of mismatched antigens, HLA class II typing of the recipient, cytokine gene polymorphisms, and cellular immunoregulatory mechanisms. De novo developed antibodies require special attention because not all DSA have equal clinical significance. Therefore, it is important for transplant clinicians and transplant immunologists to accurately characterize DSA. In this review, the contemporary immunological techniques for detection and characterization of anti-HLA antibodies and their pitfalls are described.

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.