Male Recipients Of Female Grafts Research Articles

Sex mismatch following heart transplantation in the United States: Characteristics and impact on outcomes.

Available literature indicates the possible detrimental effect of sex mismatching on mortality in patients undergoing heart transplantation. Our objective was to examine the role of sex and heart mass (predicted heart mass [PHM]) mismatch on mortality and graft rejection in patients undergoing heart transplantation in the US. Data on adult patients who underwent heart transplantation between January 2015 and October 2021 were queried from the United Network of Organ Sharing (UNOS) registry. The main outcomes were all-cause mortality, 1-year all-cause mortality and treated acute rejection. A total of 19805 adult patients underwent heart transplant during the study period. 92.2% of the patients in the female graft to male group had a PHM mismatch <25%, while only 38.5% had such a mismatch in the male graft to female group. In male to male and female to female groups, 79% and 76% of the patients had a PHM mismatch <25% (p=.122). Proportion of PHM mismatch was similar throughout the study period. Unadjusted analysis showed that male recipients of female grafts had increased risk for all-cause mortality (hazard ratio [HR]: 1.13; 95% confidence intervals [CI]: 1.02, 1.27; p=.026) and 1-year mortality (HR: 1.26; 95% CI: 1.09, 1.45; p=.002) compared to male recipients of male grafts. Graft failure incidence was also higher (HR: 1.12; 95% CI: 1.01, 1.25; p=.041). However, all these associations were non- significant after risk factor adjustment. Sex mismatching is associated with post-transplant mortality with transplantation of female donor grafts to male recipients demonstrating worse outcomes, although this association disappears after risk factor adjustment. Further research is required to elucidate the need for potential changes in clinical practice.

Alloimmunization To HLA Class I Antigens But Not H-Y Antigens Is Associated With Transfusion In Children With Sickle Cell Disease

IntroductionPatients with sickle cell disease (SCD) are at high risk for graft rejection after hematopoietic stem cell transplant (HSCT) especially when using reduced intensity conditioning (RIC). Alloimmunization from red blood cell (RBC) transfusions, critical to the management of SCD, may predispose these patients to HSCT rejection. Alloimmunization to major or minor histocompatibility antigens (mHA) may occur after RBC transfusion due to residual white blood cells or platelets present in RBC units even after leukoreduction. In mice, despite extensive leukoreduction, RBC transfusions caused alloimmunization and subsequent HSCT rejection after RIC.We conducted a cross-sectional study to determine if RBC transfusions are associated with alloantibody formation to human leukocyte antigens (HLA) and mHA, the target of the host versus graft rejection in HLA-identical transplantation. For mHA, we assessed immunity to H-Y antigens, mHA encoded on the Y chromosome. We have previously demonstrated the importance of H-Y antibodies in a variety of settings including chronic graft versus host disease (in male recipients of female grafts) and rejection of renal transplants (in female recipients of male grafts). MethodsWe enrolled 114 nulliparous pediatric SCD (SS or Sβ0) patients: 58 females on chronic transfusion, 32 males on chronic transfusion, and 24 females who had never been transfused. Serum was evaluated for HLA antibodies using the FlowPRA® (panel reactive antibody) screening test which detects IgG antibodies to the majority of HLA class I and II antigens. Serum was also tested for IgG antibodies against 5 H-Y antigens (DDX3Y [DBY], EIF1AY, RPS4Y1, UTY, ZFY) using protein microarray technology with each H-Y-seropositive threshold determined as a microarray mean fluorescence intensity (MFI) > the median MFI + 2.5 quartiles measured in 60 adult healthy males. ResultsChronically transfused patients had a higher prevalence of HLA class I antibodies than never transfused patients (33.3% vs. 12.5%, p=0.074). This increased prevalence of HLA class I antibodies in the chronic transfusion group was significant when examining the number of patients who tested positive to more than 25% of the panel (17.8% vs. 0%, p=0.022). Few patients had detectable HLA class II antibodies with no significant differences between chronically transfused and non-transfused patients.Few SCD patients had detectable H-Y alloantibodies with no significant differences in chronically transfused females, chronically transfused males, and non-transfused females.Chronic Transfusion (n=90)Never Transfused (n=24)PHLA class I PRA >3%30 (33.3%)3 (12.5%)0.074HLA class I PRA >25%16 (17.8%)0 (0%)0.022*HLA class II PRA >3%6 (6.7%)3 (12.5%)0.39HLA class II PRA >25%3 (3.3%)1 (4.2%)1.00HLA class I or II PRA >3%33 (36.7%)6 (25.0%)0.34H-Y antigenChronic Transfusion Female (n=58)Chronic Transfusion Male (n=32)Never Transfused Female (n=24)DBY1 (1.7%)0 (0%)0 (0%)EIF1AY0 (0%)0 (0%)0 (0%)RPS4Y12 (3.4%)0 (0%)0 (0%)UTY2 (3.4%)2 (6.3%)1 (4.2%)ZFY1 (1.7%)0 (0%)0 (0%)Any H-Y4 (6.9%) [p= 0.90]2 (6.3%)1 (4.2%) ConclusionsLeukocyte-reduced RBC transfusions appear to engender immunization to class I HLA but not class II HLA or H-Y antigens in pediatric SCD patients. Since hematopoietic progenitor cells express class I HLA, transfusion-related immunity to these antigens could pose a barrier to engraftment in HLA-disparate transplants. Since these antigens are also expressed on platelets, class I HLA antibodies in SCD could have important implications for platelet transfusion support during HSCT. While RBC transfusion does not appear to be an adequate stimulus for H-Y alloantibody formation, it is possible that exposure to mHA during transfusion could cause a cellular rather than a humoral immune response that may contribute to future HSCT graft rejection. Our result that few (6%) nulliparous female children with SCD had detectable H-Y alloantibodies is also a significant finding considering that 19-41% of healthy adult females had antibodies to at least one H-Y antigen in previous studies. Finally our finding that 25% of never transfused children with SCD had a positive HLA PRA is unexpected for an “unsensitized” group; its significance is being further investigated. Disclosures:No relevant conflicts of interest to declare.

Tregs Specific for Minor Histocompatibility Antigens

Abstract 1891 Background:The risk of acute GVHD after HSCT is increased in male recipients of female grafts. Disparities for the male-associated H-Y and other minor histocompatibility antigens (mHAs) have the capacity to sensitize alloreactive donor T cells and cause GVHD in HLA-matched recipients. These mHAs are polymorphic proteins that differ between donor and recipient and are presented as peptides by HLA molecules on recipient or donor antigen-presenting cells to donor immune cells. Currently, there is no evidence that minor histocompatibility antigen specific Tregs exist. Earlier in our laboratory, we have measured the frequency, growth requirements, and function of human blood Tregs specific for allo-MHC. In the present study, we sought to detect the frequency, expansion kinetics and characteristics of the minor antigens specific Tregs in the blood of HLA-matched sibling pair. Methods:CD4+CD25+CD127− Tregs were isolated by immunoabsorption from sibling donors, and cultured with HLA-matched sibling recipient antigen-presenting cells in the presence of IL-2, IL-15 and rapamycin. We detected 30–50 fold increase in H-TdR uptake at 6 days in Treg cultures stimulated by HLA-identical sibling compared to self DC. The precursor frequency of mHA-specific Tregs are between 7 and 43 (median - 13) cells per one million blood Tregs. The frequency of mHA-specific conventional CD4 T cells among total blood CD4 T cells is similar in HLA-matched sibling donors. Ex vivo expanded mHA-specific Tregs maintained higher levels of Foxp3 expression, retained the lymphoid homing receptor CD62L and a chemokine receptor, CCR7, suggesting that they are functional and are able to migrate to lymphoid tissue in vivo. Split well assay on day 12 demonstrated the mHA specificity, since Treg responded to restimulation with DC from the original HLA-identical sibling, but not self DC. The mHA-specific Tregs expanded to more than 100 fold in vitro, and exhibited antigen specific suppression. When Tregs were cultured at limiting dilution, we obtained 6 mHA-specific Treg clones that retained TGF-beta secretion in response to the sibling's mHA-disparate DC but not self DC. Conclusion:We demonstrated for the first time that it is possible to detect and expand mHA specific Tregs from HLA-matched sibling pairs, immunotherapy with mHA-specific Tregs may prevent GVHD. Disclosures:No relevant conflicts of interest to declare.

Frequency and Intensity of Antibody Responses to Antigens Encoded by KDM5D (SMCY) and Other H-Y Genes After Allogeneic Hematopoietic Cell Transplantation,

Abstract 4028Male recipients of female hematopoietic cell grafts (F->M HCT), when compared with other donor/recipient gender combinations, face an increased risk for both acute and chronic graft-versus-host disease (GVHD), but also have a significantly decreased risk of posttransplant relapse. F->M HCT is characterized at the cellular level by female donor T cell responses against male-specific minor histocompatibility (H-Y) antigens, which can contribute to both GVHD and graft-versus-leukemia (GVL) activity. Data from both murine models and clinical studies of allogeneic HCT demonstrate that the protein product of the Y chromosome gene KDM5D (previously known as SMCY) is one of the major targets of H-Y-specific T cell responses. CD8+ T cell responses against KDM5D peptides have been associated with GVHD and GVL in male recipients of female grafts, and with rejection of male grafts by female recipients.A subset of Y chromosome-encoded proteins, including several that are targets for CD8+ and CD4+ T cell responses after F->M HCT, are also the targets of antibody responses in this setting (Miklos et al., Blood 2005; 105:2973). Antibody responses to the protein products of DDX3Y and UTY, in particular, have been detected in up to 50% of F->M HCT recipients. Moreover, antibody responses to these Y chromosome gene products have been associated with the development of chronic GVHD as well as the maintenance of remission. T cell responses to KDM5D in F->M HCT recipients have been extensively studied, but KDM5D-reactive antibody responses have not been thoroughly evaluated. We hypothesized that KDM5D -reactive antibodies would also develop in a significant fraction of F->M HCT recipients, and undertook an exploratory study to define the frequency and intensity of antibody responses to KDM5D in both allogeneic HCT patients and healthy adult male and female control subjects.Plasma samples were obtained from 39 male HCT patients with female donors, 16 HCT patients with other donor/recipient gender combinations, 12 healthy female controls, and 9 healthy male controls, and assessed for IgG responses against an array of 84 different protein targets by ELISA. The target panel included partial (SMCY and UTY) or whole (DDX3Y, ZFY RPS4Y, and E1F1AY) recombinant H-Y proteins and their X chromosome-encoded homologues that had been expressed in and purified from E. coli, as well as synthetic overlapping peptides of length 15–21 residues derived from the KDM5D and DDX3Y protein sequences or from their X chromosome-encoded homologues KDM5C (SMCX) and DDX3X. Of the 55 samples acquired from HCT recipients, 49 came from recipients who had previously been diagnosed with cGVHD and were receiving immunosuppressive therapy.Reactivity with KDM5D-derived peptides or recombinant KDM5D protein fragments was observed in HCT recipients of all four donor-recipient gender combinations and also in some healthy control males and females. Amongst male patients with female donors, 7 of 39 (18%) samples were reactive with more than 3 KDM5D peptides, and 2 of 16 (13%) samples from patients with other donor/recipient gender combinations were reactive with 3 or more KDM5D peptides. Significant differences in the frequency of reactivity with individual peptides were observed, with a high frequency of responses to peptides corresponding to sequences within the interval KDM5D281–375, a region of the protein where there is significant nonidentity with the sequence of its X chromosome-encoded homologue KDM5C. This region also contains the sequence FIDSYICQV, which comprises the epitope recognized by CD8+ HLA-A*0201-restricted T cell clones that have frequently been isolated from HLA-A*0201+ F->M HCT recipients and have been associated with both GVHD and GVL. Antibody reactivity to KDM5D was correlated with reactivity to several DDX3Y-derived peptides previously shown to be the targets of antibody responses in F->M HCT recipients, but weakly associated with responses to UTY protein fragments, which were observed in 11 of 39 (28%) F->M patients and 1 of 16 (6%) patients with other donor/recipient gender combinations. These results suggest that KDM5D is a frequent target of posttransplant antibody responses in allogeneic HCT recipients. Current studies are evaluating in a larger cohort of patients the relationship of KDM5D-reactive antibody responses to H-Y-specific T cell responses and to the development of acute and chronic GVHD. Disclosures:No relevant conflicts of interest to declare.

In Situ Detection of HY-Specific T Cells in Acute Graft-versus-Host Disease–Affected Male Skin after Sex-Mismatched Stem Cell Transplantation

HY-specific T cells are presumed to play a role in acute graft-versus-host disease (aGVHD) after female-to-male stem cell transplantation (SCT). However, infiltrates of these T cells in aGVHD-affected tissues have not yet been reported. We evaluated the application of HLA-A2/HY dextramers for the in situ detection of HY-specific T cells in cryopreserved skin biopsy specimens. We applied the HLA-A2/HY dextramers on cryopreserved skin biopsy specimens from seven male HLA-A2(+) pediatric patients who underwent stem cell transplantation with confirmed aGVHD involving the skin. The dextramers demonstrated the presence of HY-specific T cells. In skin biopsy specimens of three male recipients of female grafts, 68% to 78% of all skin-infiltrating CD8(+) T cells were HY-specific, whereas these cells were absent in biopsy specimens collected from sex-matched patient-donor pairs. Although this study involved a small and heterogeneous patient group, our results strongly support the hypothesis that HY-specific T cells are actively involved in the pathophysiology of aGVHD after sex-mismatched stem cell transplantation.

Modeling Chronic Graft-Versus-Host-Disease: A New MHC-Matched Model of Late-Onset Scleroderma After Low-Dose Conditioning and Hematopoietic Cell Transplantation That Affects Only Male Recipients of Female Grafts.

Abstract 3560Poster Board III-497Chronic graft-vs-host disease (GVHD) is the most common late complication of allogeneic hematopoietic cell transplantation (HCT), is associated with high morbidity, and presents a major problem even after reduced intensity conditioning. Many aspects of the syndrome, such as sclerodermatous skin changes resemble autoimmune diseases. Unlike acute GVHD, which is a donor T cell (TC) driven inflammatory event, the pathophysiology of chronic GVHD remains poorly elucidated. One reason for this limited understanding is the lack of mouse models that recapitulate the late-onset scenario of collagenous sclerosis observed in humans. Here, we present a MHC-matched model in which mice develop profound sclerotic skin changes beyond day (d) 100 post-HCT. Importantly, the syndrome occurs only in males receiving female grafts, a donor/recipient gender combination which in humans is associated with increased risk of developing chronic GVHD. FACS-purified hematopoietic stem cells (HSC: cKIT+Thy1.1loSca1+Lin-) alone or supplemented with TC from female AKR/J donors were infused into sublethally (4 Gy) irradiated BALB.K mice (both H2k). Recipients underwent a transient phase of mild acute GVHD (skin reddening, weight loss), but recovered fully. While none of 24 female hosts displayed any signs of chronic GVHD over an observation period of more than 200d, 17 of 27 males (63%) developed massive skin thickening with severe bruising and excoriations. The progressively indurated lesions appeared between d100-200, primarily on the trunk, were tightly fixed to the underlying fascia, and subsequently resulted in alopecia. Histologically, hyperkeratosis and massive thickening of trichrome-positive collagen bundles in dermis and subcutis predominated the picture. Late-onset scleroderma was not associated with significant weight loss or rapid death. In this non-myeloablative setting all mice with chronic GVHD were mixed chimeras in their myeloid, T and B cell lineages. Mice that had rejected their grafts remained healthy. The composition of mononuclear cells (MNC) in bone marrow (BM), spleen (SP), lymph nodes (LN), thymus, liver, and skin of affected animals was FACS analyzed and compared with disease-free female recipients and normal controls. Chronic GVHD afflicted mice had B lymphopenia (30-50% decrease) in BM, SP and LN. Both donor and host TC were increased in the livers (each 7-17%), but normal in the other organs. NK cells were markedly reduced in liver (1-2.5%) and SP (<1%), compared with unmanipulated BALB.K mice which have ∼5% NK cells in liver and SP. Single cell suspensions of MNC infiltrating the skin were made by enzymatic digestion, enriched using a Ficoll gradient, and analyzed by FACS, Wright Giemsa staining, and PCR for chimerism assessment of sorted cell subsets. Regarding their morphology on cytospin slides the majority of skin MNC resembled macrophages with a central small round nucleus and a low nuclear / cytoplasmic ratio. By FACS 35-55% of cells were Mac1high (vs 8% in females and controls), 20-35% Mac1lo (vs 15-20%). Mac1high cells comprised granulocytes (30% Gr1+), mature NK cells (∼30% DX5+CD122+), and macrophages (Gr1-DX5-). Skin of affected mice (but not females and controls) also contained 15-25% CD4 TC, but only few CD8 TC (1-5%), and no B cells. Neither in the skin nor in any other organ did PMA-stimulated lymphocytes express increased amounts of IFNγ or IL-17. All cellular subsets were mixed chimeric. In summary: here, we present a novel MHC-matched model of non-myeloablative HCT that resembles human chronic GVHD in many key aspects, including late onset, development of scleroderma-like fibrosis, preponderance of male recipients given female grafts, and no clear association to graft type. Similarities with autoimmune scleroderma are striking with regard to increased thickness of the skin with hyperkeratosis, broad sclerotic collagen bundles in dermis and subcutis, predominance of CD4 over CD8 TC, presence of macrophages, and mixed microchimerism in the skin. We continue to pursue the identity of the cells responsible for this syndrome and the targets of immune reactivity. Disclosures:Miklos:Novartis: Research Funding.

H-Y as a minor histocompatibility antigen in kidney transplantation: a retrospective cohort study

In haematopoietic stem-cell transplantation, male recipients of female grafts have an increased risk of graft-versus-host disease and female recipients have both an increased risk of rejection of male grafts and of specific T-cell and antibody reactivity against H-Y encoded gene products. By contrast, in kidney transplantation, the role of H-Y as a minor histocompatibility antigen has been disputed. We aimed to investigate whether an immunological H-Y effect occurs in kidney transplantation. We did a retrospective cohort study between 1985 and 2004 in 195 516 recipients of allografts from deceased donors. We used multivariate statistical methods to compare graft survival and death-censored graft survival rates for female and male donor kidneys in female and male recipients at 1 and 10 years. Graft loss was more common with kidneys from female donors than with those from male donors (p<0.001) after both 1 and 10 years. Female recipients had a lower rate of graft failure between the end of the first year and the end of the tenth year (p<0.001). Compared with all other combinations of sex, transplantation of male donor kidneys into female recipients was associated with an increased risk of graft failure during the first year (hazard ratio [HR] 1.08, 95% CI 1.03-1.14, p=0.003; death censored HR 1.11, 1.04-1.19, p=0.003) and between 2 and 10 years (HR 1.06, 1.01-1.10, p=0.008; death censored HR 1.10, 1.05-1.16, p<0.001). H-Y minor histocompatibility affects human kidney transplantation.

Impact of the Donor Recipient Sex Combination in Hematopoietic Stem Cell Transplantation: H-Y as a Model for the Interaction between Major and Minor Histocompatibility Antigens.

The importance of minor histocompatibility antigens (miHAg) on outcome in hematopoietic stem cell trans-plantation (HSCT) is well described. H-Y encoded miHAg's were one of the first to be identified as clinically relevant genetic factors outside HLA. A higher risk of graft-versus-host disease (GvHD) in male recipients of female grafts, specific H-Y directed T-cell responses and antibody reactivity have been documented. As a beneficial effect, a reduced risk of relapse has been observed. Still, the role of H-Y miHAg's has been disputed in some studies. We studied the effects of the donor recipient sex combination of 63′609 patients (59% male, 41% female, median age 33 years, range 0 to 77 years) with an allogeneic HSCT transplanted between 1980 and 2005 and reported to the EBMT. Main diagnoses were acute leukemias (32′671; 51%), chronic leukemias (15′167; 24%), lymphomas (3901; 6%), plasma cell disorders (1643; 3%), MDS/MPS (5′678; 9%) and aplastic anemia (4459; 7%). Patients were stratified by disease, disease stage (good (55%), intermediate (26%), high risk (19%)), stem cell source (bone marrow (62%), peripheral blood (36%), cord blood (2%)), age (<20 years (27%), 20–40 years (41%), >40 (32%) years), donor age (<20 (21%), >20 (79%) years), conditioning intensity (myeloablative (86%), RIC (14%) and year of transplant. Endpoints analysed were cumulative risks of transplant related mortality (TRM) or relapse (REL) and probability of survival. Results of multivariate analyses are presented. There was a 15% higher relative risk of TRM in male patients receiving a female donor (RMDF) transplant compared to all other gender combinations (RR 1.15; 1.12–1.19). Despite a 9% significant reduction in relapse (RR 0.91; 0.88–0.95), overall survival remained worse (RR 1.08; 1.05–1.11). A higher TRM for RMDF was seen over all calendar years, in all disease categories, disease stages, age classes and with all stem cell sources, with a few distinct exceptions: it was not seen in patients with donors <20 years (RR 0.98; 0.9–1.1), it was not observed in patients with lymphoma (RR 1.06; 0.93–1.20) and it was not observed in the cord blood cohort (RR 0.8; 0.62–1.04). In view of the discordant effects on TRM and REL, the relative impact on survival varied, depending on disease, disease stage and age; e.g., survival was similar in high risk patients for the RMDF and “other” group. Moreover, the higher TRM with RMDF was limited to HLA-identical sibling transplants (RR 1.22; 1.17–1.26) and matched unrelated transplants (RR 1.22; 1.13–1.32). It was neither observed in mismatched related (RR 0.97; 0.87–1.08) nor in mismatched unrelated HSCT (RR 1.03; 0.91–1.18). These data clarify the role of the donor recipient sex combination and form the basis for donor selection algorithms. In addition, they substantiate the close interaction between major and minor histocompatibility antigens: the higher the degree of matching for HLA-antigens, the higher the impact of H-Y difference. It is likely, that the same mechanisms will hold true for other miHAg's as well.

Impact of donor gender on male rat recipients of small-for-size liver grafts

The aim of this study was to assess the impact of donor gender on small-for-size (SFS) liver transplantation in male recipients using a rat model. Adult female or male Lewis rats were used as donors and male Lewis rats as recipients. Size-matched (SM) and SFS liver grafts from either male or female donors were transplanted into male recipients. Animals receiving SFS grafts were sacrificed at postoperative week 1, week 4, and week 12, respectively (n = 6-8 per group), those receiving SM grafts after 3 months. The cumulative survival rate (SVR) in the female-to-male (F-M) SFS group was significantly lower (62%; 13 of 21) compared with the male-to-male (M-M) group (90%; 18 of 20) (P < 0.05). Spontaneous death occurred in the F-M SFS combination either in the early postoperative period (<3 weeks) in animals with confluent hepatic necrosis or in the late postoperative period (>8 weeks) in animals with biliary obstruction. In contrast, no death was observed in the early posttransplantation period after M-M liver transplantation. The relative graft size in the SM F-M group was significantly higher (graft-to-recipient weight ratio [GRWR] 2.40% +/- 0.8%) than in the SFS M-M group (GRWR 1.35% +/- 0.2%; P < 0.001). Regardless of graft size, the outcome was worse in terms of SVR as well as regarding the incidence and severity of biliary complications in F-M compared with M-M liver transplantation. In conclusion, male recipients of female livers had a less favorable outcome irrespective of graft size. Confluent hepatic necrosis as well as biliary obstruction were perceived as consequence of a severe perfusion problem in F-M liver transplantation, which was possibly related to an enhancement of ischemia-reperfusion (I/R) injury by the lack of estrogen in male recipients of female grafts.