Etsuko Maruya

Epitopes of human leukocyte antigen class I antibodies found in sera of normal healthy males and cord blood

This study defines 96 epitopes targeted by human leukocyte antigen (HLA) antibodies reported in the sera of normal healthy males with no history of deliberate alloimmunizations and in cord blood. These epitopes are accessible for antibody binding on either the intact or the dissociated forms of recombinant HLA class I single antigens. Sixty percent of the epitopes are accessible on dissociated antigens, are defined mostly by hidden amino acids, and are designated as cryptic epitopes. All 96 epitopes are located exclusively on A-, B-, or C-locus antigens except for one interlocus epitope. All sera in this study were tested in parallel, using single antigen beads that bear either intact or dissociated HLA antigens and antibodies with nearly identical specificities were identified in all tested sera. Because the specificities of these naturally occurring antibodies are unavoidably detected when testing for specificities of alloantibodies, it may be necessary to clearly differentiate the two forms of antibody. To date, the relevance of these antibodies in transplantation is unknown, but even if they are determined to be irrelevant to graft rejection, awareness of the newly identified epitopes could prove useful in avoiding the unnecessary exclusion of potential transplant donors.

Risk and prevention of graft failure in patients with preexisting donor-specific HLA antibodies undergoing unmanipulated haploidentical SCT.

A role of donor-specific HLA antibodies (DSA) in graft failure after SCT has been suggested, but the relevance of DSA in unmanipulated haploidentical SCT (haplo-SCT) remains unknown. We prospectively examined HLA antibodies using the Luminex-based single Ag assay for 79 adult patients undergoing unmanipulated haplo-SCT. Among them, 16 (20.2%) were HLA Ab-positive, including five patients with antibodies not corresponding to donor HLA Ags and 11 DSA-positive patients. Of the 11 DSA-positive patients, five received treatments to decrease DSA levels, including two, who received plasma exchange and rituximab, two who received platelet transfusions from healthy-related donors having DSA-corresponding HLA Ags and one who received bortezomib. Platelet transfusion was the most simple and effective treatment option for class I DSA. The cumulative incidence of neutrophil recovery was significantly lower in pretransplant (post-treatment) DSA-positive patients than in DSA-negative patients (61.9 vs 94.4%, P=0.026). Notably, three of five patients with high levels of DSA had graft failure. Donors should be selected on the basis of an evaluation of HLA antibodies. If haplo-SCT from donors with HLA Ags that correspond to high levels of DSA must be performed, then recipients should be treated for DSA to improve the chances of successful donor engraftment.

Long-term Feto-Maternal Microchimerism : Nature's Hidden Clue for Alternative Donor Hematopoietic Cell Transplantation?

During pregnancy, fetal hematopoietic cells carrying paternal human leukocyte antigens (HLA) migrate into maternal circulation, and, vice versa, maternal nucleated cells can be detected in fetal organs and umbilical cord blood, indicating the presence of bidirectional cell traffic between mother and fetus. By taking advantage of fluorescence in-situ hybridization or polymerase chain reaction-based techniques, researchers recently found that postpartum persistence of such reciprocal chimerism was common among healthy individuals and may sometimes cause tissue chimerism.Although the biological significance of long-lasting feto-maternal microchimerism is unknown, a number of investigations have suggested its association with the development of “autoimmune” diseases such as systemic sclerosis. However, the very common presence of feto-maternal microchimerism among subjects without any autoimmune attack may allow us the more appealing hypothesis that it is an indicator for the acquired immunological hyporesponsiveness to noninherited maternal or fetal HLA antigens. An offspring’s tolerance to noninherited maternal antigens has been clinically suggested by the retrospective analysis of renal transplantations or haploidentical hematopoietic stem cell transplantations, and whether postpartum mothers can tolerate paternally derived fetal antigens is an intriguing question. Although an exact linkage between microchimerism and transplantation tolerance is yet to be elucidated, long-term acceptance of a recipient’s cell in the donor may have a favorable effect on preventing the development of severe graft-versus-host disease, and the donor cell microchimerism in the recipient might facilitate the graft acceptance. If this concept holds true, HLA-mismatched hematopoietic stem cell transplantation would be more feasible among haploidentical family members mutually linked with feto-maternal microchimerism. Further studies are warranted to investigate the potential role of feto-maternal microchimerism in human transplantation medicine.

Anti-citrullinated peptide antibody-negative RA is a genetically distinct subset: a definitive study using only bone-erosive ACPA-negative rheumatoid arthritis

Objectives. ACPA is a highly specific marker for RA. It was recently reported that ACPA can be used to classify RA into two disease subsets, ACPA-positive and ACPA-negative RA. ACPA-positive RA was found to be associated with the HLA-DR shared epitope (SE), but ACPA negative was not. However, the suspicion remained that this result was caused by the ACPA-negative RA subset containing patients with non-RA diseases. We examined whether this is the case even when possible non-RA ACPA-negative RA patients were excluded by selecting only patients with bone erosion. Methods. We genotyped HLA-DRB1 alleles for 574 ACPA-positive RA, 185 ACPA-negative RA (including 97 erosive RA) and 1508 healthy donors. We also tested whether HLA-DR SE is associated with RF-negative or ANA-negative RA. Results. ACPA-negative RA with apparent bone erosion was not associated with SE, supporting the idea that ACPA-negative RA is genetically distinct from ACPA-positive RA. We also tested whether these subsets are based on autoantibody-producing activity. In accordance with the ACPA-negative RA subset, the RF-negative RA subset showed a clearly distinct pattern of association with SE from the RF-positive RA. In contrast, ANA-negative as well as ANA-positive RA was similarly associated with SE, suggesting that the subsets distinguished by ACPA are not based simply on differences in autoantibody production. Conclusions. ACPA-negative erosive RA is genetically distinct from ACPA-positive RA.

New Platelet Antigen, Siba, Involved in Platelet Transfusion Refractoriness in a Japanese Man

Abstract. Siba, a new platelet‐specific alloantigen involved in a case of platelet transfusion refractoriness is reported. The IgG platelet alloantibody was detected in a multiply transfused patient of Japanese extraction (Sib), by the presence of HLA antibodies. After transfusion of HLA‐compatible platelets, the patient suffered from refractoriness. Adsorption studies with pooled lymphocytes showed that the serum contained anti‐platelet activity. Family studies indicate that Siba is inherited as an autosomal codominant trait and separate from HLA and Baka. As of this report, segregation from Zw (PlA) and Yuk (Pen) antigen systems have not yet been determined. The gene frequency of Siba in the Japanese population is estimated to be 0.136.

Association between type 1 diabetes age-at-onset and intercellular adhesion molecule-1 (ICAM-1) gene polymorphism

We investigated the intercellular adhesion molecule-1 (ICAM-1) gene polymorphism in 90 patients with young-onset type 1 diabetes, 74 with adult-onset type 1 diabetes, and 171 control subjects. The distribution of C-T genotypes and allele frequencies in exon 6 of the ICAM-1 gene was significantly different between adult-onset type 1 diabetes patients and controls (chi(2) = 9.76, p = 0.0076), and between patients with adult-onset and young-onset type 1 diabetes (chi(2) = 11.28, p = 0.0036). In contrast, we failed to detect any association between patients with young-onset type 1 diabetes and controls. Our data suggest that ICAM-1 exon 6 gene polymorphism affects the age-at-onset of type 1 diabetes and that different pathogenetic mechanisms may exist between young-onset and adult-onset type 1 diabetes.

Antibody Removal Therapy Used Successfully at Delivery of a Pregnant Patient with Glanzmann's Thrombasthenia and Multiple Anti‐Platelet Antibodies

Abstract. A 31‐year‐old Japanese woman with Glanzmanns thrombasthenia became pregnant voluntarily. She had had transfusions with more than 60 units for severe bleeding. She had multiple antibodies against HLA antigens and platelet glycoprotein Ilb/IIIa. No compatible platelets were available. To prevent serious hemorrhage during her delivery, antibody removal therapy was carried out three times. Large molecules including immunoglobulins were removed from more than 3 liters of plasma each time. After the titer of antiplatelet antibodies had decreased in the patients blood, antihuman globulin‐lymphocyte cytotoxicity test compatible platelets were transfused. Her bleeding time improved and delivery was induced successfully despite atonic hemorrhage of about 2,000 g of blood. Her infant had no bleeding problems. This patient is the first with Glanzmanns thrombasthenia to receive antibody removal therapy at delivery.

One‐way donor‐recipient HLA‐matching as a risk factor for graft‐versus‐host disease in living‐related liver transplantation

Abstract Although one‐way matching between an HLA‐homozygous donor and a haploidentical recipient is a recognized risk factor in transfusion‐associated graft‐versus‐host disease (GVHD), its impact in living‐related liver transplantation (LRLT) has so far not been investigated. We present a case of fatal acute GVHD in our LRLT program that was attributed to one‐way HLA matching between donor and recipient. Although the disappearance of donor cells in peripheral blood was suggested by genetic analysis, severe septicemia led to a fatal outcome. We further reviewed 280 LRLT cases and correlated one‐way HLA matching with outcome. A total of 8 out of 280 donors (2.9%) and 11 out of 278 recipients (4.0%) were completely HLA homozygous in our LRLT program. Complete one‐way HLA matching linked to GVHD was observed in four cases, including the present case. Although other contributing factors also need to be clarified, one‐way HLA matching is a definite risk factor for GVHD in LRLT. We advocate caution before proceeding with one‐way HLA donor‐recipient combinations.

A large-scale association study identified multiple HLA-DRB1 alleles associated with ACPA-negative rheumatoid arthritis in Japanese subjects

Background HLA-DRB1 is associated with rheumatoid arthritis (RA). However, it has recently been suggested that HLA-DRB1 is only associated with patients with RA who have anticitrullinated peptide/protein antibodies (ACPA), which are specific to RA. Objective To elucidate whether specific HLA-DR alleles are associated with ACPA-negative RA development. Methods HLA-DRB1 typing was carried out in 368 Japanese ACPA-negative patients with RA and 1508 healthy volunteers as the first set, followed by HLA-DRB1 typing of 501 cases and 500 controls as the second set. The HLA-DRB1 allele frequency and diplotype frequency were compared in each group, and the results of the two studies were combined to detect HLA-DRB1 alleles or diplotypes associated with ACPA-negative RA. Results HLA-DRB1*12:01 was identified as a novel susceptibility allele for ACPA-negative RA (p=0.000088, OR=1.72, 95% CI 1.31 to 2.26). HLA-DRB1*04:05 and *14:03 showed moderate associations with ACPA-negative RA (p=0.0063, OR=1.26, 95% CI 1.07 to 1.49 and p=0.0043, OR=1.81, 95% CI 1.20 to 2.73, respectively). The shared epitope was weakly associated with ACPA-negative RA, but no dosage effect was detected (p=0.016, OR=1.17, 95% CI 1.03 to 1.34). A combination of HLA-DRB1*12:01 and DRB1*09:01 showed a strong association with susceptibility to ACPA-negative RA (p=0.00013, OR=3.62, 95% CI 1.79 to 7.30). Homozygosity for HLA-DR8 was significantly associated with ACPA-negative RA (p=0.0070, OR=2.16, 95% CI 1.22 to 3.82). It was also found that HLA-DRB1*15:02 and *13:02 were protective against ACPA-negative RA (p=0.00010, OR=0.68, 95% CI 0.56 to 0.83 and p=0.00059, OR=0.66, 95% CI 0.52 to 0.84, respectively). Conclusions In this large-scale association study multiple alleles and diplotypes were found to be associated with susceptibility to, or protection against, ACPA-negative RA.

Tumour regression following stem cell infusion from daughter to microchimeric mother

Fetal cells are known to persist in mothers for many years. We report a patient with poorly differentiated epithelial thymic carcinoma who had a large anterior mediastinal tumour, pericardial mass, left upper and right middle lobe tumour masses, and right liver mass. She received a single infusion of 10(10) stem cells from her 32-year-old daughter. Before the transfusion, she had had persistent chimeric cells from her daughter. The tumour regressed after stem cell infusion and has remained in regression for over 1 year. The daughters cells were present at 330 days post infusion.