HLA Factors Research Articles

Haploidentical vs HLA-matched sibling donor HCT with PTCy prophylaxis: HLA factors and donor age considerations

AbstractHLA-matched sibling donors (MSDs) are preferred for hematopoietic cell transplantation (HCT). However, the use of alternative donors, especially haploidentical, is increasing, as is our understanding of the impact of HLA factors such as B-leader and DRB1-matching on its outcomes. Yet, data comparing these donor types, particularly considering these HLA factors, is lacking. Herein, we compared haploidentical-HCT (n = 1052) with MSD-HCT (n = 400), both with posttransplant cyclophosphamide (PTCy)-based graft-versus-host disease prophylaxis. In multivariate analysis, haploidentical group had similar overall survival (OS; hazard ratio (HR), 0.94; 95% confidence interval [CI], 0.78-1.14; P = .54), nonrelapse mortality (HR, 0.98; 95% CI, 0.72-1.32; P = .87), and relapse (HR, 0.87; 95% CI, 0.70-1.08; P = .20) as the MSD group. Younger donor age was a significant predictor of improved OS. Next, we directly compared the outcomes of “younger” haploidentical (donor age <35 years, n = 347) vs an “older” MSD (donor age ≥50 years, n = 143) in older recipients (patient age ≥50 years). Patients with younger haploidentical B-leader–matched donors had significantly superior OS (HR, 0.65; 95% CI, 0.48-0.90; P = .009) than the older MSD group. Additionally, patients with younger DRB1-mismatched haploidentical donors (HR, 0.63; 95% CI, 0.46-0.87; P = .004) had significantly lower risk of relapse than older MSDs. Our study suggests that haploidentical-HCT may offer comparable outcomes to MSD-PTCy HCT. Moreover, among older patients, a younger haploidentical B-leader–matched donor might be preferable to an older MSD. These findings need validation in larger data sets.

Haploidentical Versus Mismatched Unrelated Donor Hematopoietic Cell Transplantation: HLA Factors and Donor Age Considerations

HLA-mismatched unrelated donors and haploidentical related donors are suitable stem cell sources for hematopoietic cell transplantation (HCT) when patients lack HLA-matched donors. Clinical outcome after mismatched HCT is influenced by HLA factors including the similarity of peptide-binding motifs (PBMs) between the patient and unrelated donor, and of the HLA-B leader in unrelated and haploidentical donors. Whether these factors can aid in the selection between mismatched unrelated and haploidentical donors is not known. To address this question, we investigated outcomes between the two donor types defined by matching for the PBM and leader peptide. We compared PBM-matched (n = 614) and mismatched (n = 958) MMUDs with calcineurin-inhibitor-based prophylaxis to four haploidentical groups that received post-transplant cyclophosphamide (PTCy)-based prophylaxis. The haploidentical groups were B-leader matched/DRB1-mismatched (n = 722), B-leader matched/DRB1-matched (n = 154), B-leader mismatched/DRB1-mismatched (n = 493), and B-leader mismatched/DRB1-matched (n = 63). Multivariate analysis showed that the B-leader matched/DRB1-mismatched haploidentical group had the best overall survival (OS) compared to the PBM-matched MMUD, while other haploidentical groups had comparable OS. The PBM-mismatched MMUD showed the poorest outcomes, similar to the B-leader mismatched/DRB1-matched haploidentical group. Among non-HLA factors, donor age was the most significant predictor of OS. These results suggest that a B-leader matched/DRB1 mismatched haploidentical donor might be the preferred choice among donors of similar age. If such a donor is not available, the youngest donor from either PBM-matched unrelated or other haploidentical groups could be a beneficial choice. These findings need validation with both donor groups receiving PTCy-based graft-versus-host disease prophylaxis.

Effect of donor age in patients with acute myeloid leukemia undergoing haploidentical hematopoietic cell transplantation vary by conditioning intensity and recipient age.

We investigated the impact of donor age (younger [≤35 years] vs. older [>35 years]) after accounting for other non-HLA and HLA factors on outcomes of patients with acute myeloid leukemia undergoing HLA-haploidentical hematopoietic cell transplantation (n = 790). The effect differed by conditioning-partly related to the differences in the recipient age in myeloablative (MAC; median 46 years) versus reduced-intensity/non-myeloablative conditioning (RIC/NMA; median 61 years) groups. With MAC (n = 320), donor age had no impact on acute graft-versus-host disease (GVHD), but older donors were associated with a significantly higher risk of chronic GVHD (hazard ratio [HR]: 1.6, 95% confidence interval [CI]: 1.10-2.30, p = .02) independent of recipient age and other factors. Donor age had no impact on either relapse or non-relapse mortality (NRM). The impact of donor/recipient age on overall survival changed over time. Older donors were associated with significantly higher late overall mortality (>6 months) in younger recipients (≤ 50 years; HR: 2.2, 95% CI: 1.03-4.6, p = .04) but not older recipients. With RIC/NMA (n = 470), neither recipient's nor donor's age influenced the risk of GVHD. Donor age had no significant impact on the risk of relapse, but older donors were associated with a significantly higher risk of NRM (HR: 1.6, 95% CI: 1.02-2.6, p = .04) independent of recipient age. Older donor age was associated with significantly higher late overall mortality (>9 months) in older recipients (>50 years; HR: 1.66, 95% CI: 1.0-2.67; p = .049) but not in younger recipients. Donor selection based on donor age may require a tailored approach for a particular recipient.

Three-Year Outcomes in Recipients of Mismatched Unrelated Bone Marrow Donor Transplants Using Post-Transplantation Cyclophosphamide: Follow-Up from a National Marrow Donor Program-Sponsored Prospective Clinical Trial

The use of post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis has resulted in reductions in GVHD and improved outcomes in allogeneic hematopoietic cell transplantation (HCT) using HLA-mismatched related donors. We report the 3-year outcomes of the first multicenter prospective clinical trial using PTCy in the setting of mismatched unrelated donor (MMUD) bone marrow HCT. The study enrolled 80 patients, treated with either myeloablative conditioning (MAC; n=40) or reduced-intensity conditioning (RIC; n=40), with the primary endpoint of 1-year overall survival (OS). The median follow-up for this study was 34 months (range, 12 to 46 months) in the RIC group and 36 months (range, 18 to 49 months) in the MAC group. Three-year OS and nonrelapse mortality were 70% and 15%, respectively, in the RIC group and 62% and 10% in the MAC group. No GVHD was reported after 1 year. The incidence of relapse was 29% in the RIC group and 51% in the MAC group. OS did not differ based on HLA match grade (63% in the 7/8 strata and 71% in the 4 to 6/8 strata). These encouraging outcomes, which were sustained for 3 years post-HCT, support the continued exploration of MMUD HCT using a PTCy platform. Important future areas to address include relapse reduction and furthering our understanding of optimal donor selection based on HLA and non-HLA factors.

HLA Factors versus Non-HLA Factors for Haploidentical Donor Selection

When multiple haploidentical donors are available for transplantation, those of younger generations are generally selected over those of older generations. However, it is unclear who is the optimal donor when selecting candidates from within a generation, such as father versus mother, son versus daughter, or brother versus sister. Although traditionally male donors are favored over female donors, particularly for male recipients, and significant associations of individual HLA mis(matches) on outcomes are being increasingly recognized, the hierarchy of factors for donor selection is indeterminate. To assess whether HLA factors take precedence over non-HLA factors and to isolate the influence of specific characteristics on outcomes, we analyzed 412 patients stratified by donor relationship: child donor (son [n = 202] versus daughter [n = 96]), parent (father [n = 28] versus mother [n = 29]), and sibling (noninherited maternal [NIMA; n = 29] versus paternal [NIPA; n = 28] mismatched). Among siblings, NIMA mismatch was associated with a lower risk of acute graft-versus-host disease (aGVHD); B-leader mismatch was associated with high nonrelapse mortality (NRM), poor progression-free survival, and a trend toward poor overall survival (OS), whereas A-mismatch was associated with lower aGVHD. Among parent donors, the relationship did not impact any outcome; B-leader mismatch was associated with higher NRM and a trend toward poor OS, whereas A-mismatch was associated with lower NRM and improved progression-free survival and OS. Among child donors, no individual HLA mismatch was predictive of any outcome, and daughter donors were not associated with any adverse outcomes in multivariate analyses. Our data suggest that certain HLA factors may be more significant in some cases and should be given priority over simply selecting a donor based on relationship/sex.

Mother Vs Father Haploidentical Donor for T Cell-Replete HCT with Ptcy Prophylaxis

Background: When several haplo donors of similar ages are available, which factors should be prioritized remains a matter of debate. This is a frequent clinical question for recipients who are undergoing haplo hematopoietic cell transplantation (HCT) from a parent donor. Although conventionally a female donor is avoided for a male recipient due to the high risk of graft-versus-host disease (GVHD), gender-mismatch (female-to-male) has not been identified as an independent predictor of worse outcomes in the setting of T cell-replete haploidentical HCT with post-transplant cyclophosphamide (PTCy) prophylaxis. On the other hand, certain (mis)matches at specific HLA loci with haplo HCT are now being recognized as predictors of survival. Thus, it has become even more ambiguous whether HLA or non-HLA factors should be prioritized for a haploidentical donor selection. Whether HLA factors trump non-HLA factors (e.g female-to-male, donor age, relationship) remains an area of active investigation. As patient and donor ages and relationships are important predictors of outcomes and are very tightly correlated to each other, we studied the effects of HLA and non-HLA factors stratified by donor relationship (mother vs father). Objective: We sought to compare the outcomes of T-cell replete haplo HCT using a mother vs father donor with PTCy prophylaxis, after accounting for (mis)matching at individual HLA loci and patient/donor age. Results: We included 57 patients with a mother (n=29) vs father (n=28) donor. Median age at HCT (23 yrs vs 27 yrs, p=0.1) and donor age (50 yrs vs 52 yrs, p=0.9) were similar in both groups. Most received RIC (79% vs 86%, p=0.5), BM graft (83% vs 75%, p=0.5), had HCT-CI >3 (46% vs 64%, p=0.2), and low/intermediate DRI (45% vs 54%, p=0.8), were CMV seropositive (86% vs 79%, p=0.04), and B-leader matched (51% vs 48%, p=0.9) and ABO matched with the donor (76% vs 64%, p=0.4). The recipient was male in 59% (mother donor) vs 61% (father donor). The median follow-up was 54 vs 28 months. Graft failure occurred in 0% vs 4%, p=0.3; the median time to neutrophil engraftment was 18 days in both groups. The cumulative incidence of grade II-IV aGVHD (65% vs 56%, p=0.3) and grade III-IV aGVHD at day 180 (31% vs 15%, p=0.2), 3-yr cGVHD (31% vs 15%, p=0.2); NRM (35% vs 26%, p=0.5), relapse (21% vs 32%, p=0.4), PFS (39% vs 36%, p=0.9) and OS was (53% vs 41%, p=0.3) in mother vs father donor, respectively. In multivariate analysis, no statistically significant differences were noted in any outcome between mother vs father donors, likely due to small number of events. However, B-leader mismatch was associated with a significantly higher risk of NRM (HR 2.7, 95% CI 1.03-7.02, p=0.04), and HLA-A mismatch was associated with a lower risk of NRM (HR 0.3, 95% CI 0.1-0.8, p=0.02), better PFS (HR 0.2, 95% CI 0.1-0.4, p<0.001) and OS (HR 0.1, 95% CI 0.05-0.4, p<0.001). HCT-CI >3 was associated with inferior PFS (HR 3.5, 95% CI 1.5-7.6, p=0.002) and OS (HR 4.1, 95% CI 1.7-9.8, p=0.002). Conclusion: HLA factors, such as B-leader mismatch (high NRM) and HLA-A mismatch (low NRM and high PFS and OS) may have a stronger prognostic impact on mortality than donor-relationship. Recognizing the limitations of the small sample size, our data suggest that among parent haplo donors, in cases where both father and mother are B-leader matched and/or HLA-A mismatched with the recipient, father should be preferred due to a 2-fold higher risk of grade III-IV aGVHD and cGVHD (although statistically non-significant) with maternal donors. However, it remains unclear whether a B-leader mismatched (and/or HLA-A matched) father be selected over a B-leader matched (and/or HLA-A mismatched) mother. Further large-scale studies are needed to comprehend these complex immunobiological relationships. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Son Vs Daughter Haploidentical Donor for T Cell-Replete HCT with Ptcy Prophylaxis

Background: A younger haplo donor is usually preferred over an older donor. However, when several donors of similar ages are available, which factors should be prioritized remains a matter of debate. This is a frequent clinical question for older recipients who are undergoing haplo hematopoietic cell transplantation (HCT) from a child donor. Although conventionally a female donor is avoided for a male recipient due to the high risk of graft-versus-host disease (GVHD), this has not been consistently seen in the setting of T cell-replete haploidentical HCT with post-transplant cyclophosphamide (PTCy) prophylaxis. Additionally, there is increasing recognition of the impact of (mis)matches at specific HLA loci with haplo HCT. Whether HLA factors trump non-HLA factors (e.g female-to-male, donor age, relationship), or vice-a-versa, is unclear. As patient and donor ages and relationships are important predictors of outcomes and are very tightly correlated to each other, we studied the effects of HLA and non-HLA factors stratified by donor relationship (son vs daughter). Objective: We sought to compare the outcomes of T-cell replete haplo HCT using a son vs daughter donor with PTCy prophylaxis, after accounting for (mis)matching at individual HLA loci and patient/donor age. Results: We included 298 consecutive patients with a daughter (n=96) vs son (n=202) donor. Median age at HCT (56 yrs vs 58 yrs, p=0.05) and donor age (27 yrs vs 29 yrs, p=0.1) were similar in both groups. Most received RIC (78% vs 76%, p=0.5) and had HCT-CI >3 (52% vs 54%, p=0.6). Fewer patients with a daughter donor received BM graft (56% vs 74%, p=0.002) and had high/very high DRI (20% vs 41%, p<0.001). Most patients were CMV seropositive (83% vs 81%, p=0.09) and ABO matched with donor (60% vs 61%, p=0.9). Significantly more patients with a daughter donor had HLA-C mismatch (97% vs 88%, p=0.01); other mismatches were similar in both groups: A (91% vs 96%, p=0.2), B-leader (43% vs 37%, p=0.6), DRB1 (92% vs 94%, p=0.5), DQB1 (86% vs 90%, p=0.3), DPB1 (76% vs 80%, p=0.4). The median follow-up was 24 vs 27 months. Graft failure occurred in 2% vs 4%, p=0.5; the median time to neutrophil engraftment was similar (20 vs 19 days). The cumulative incidence of grade II-IV aGVHD (39% vs 34%, p=0.5) and grade III-IV aGVHD at day 180 (12% vs 6%, p=0.1), 2-yr cGVHD (18% vs 12%, p=0.4); NRM (28% vs 33%, p=0.5), relapse (24% vs 29%, p=0.4), PFS (47% vs 38%, p=0.2) and OS (50% vs 46%, p=0.4) were similar in daughter vs son, respectively. In multivariate analysis, daughter donors were associated with similar risk of grade II-IV aGVHD (HR 1.2, 95% CI 0.8-1.9, p=0.3), cGVHD (HR 1.03, 95% CI 0.5-2.3, p=0.9), and NRM (HR 0.9, 95% CI 0.6-1.4, p=0.7) as sons. For survival, significant interactions were noted between donor gender and DRI. In patients with low DRI, there was no impact of donor gender, but in patients with high/v high DRI, daughter donors were associated with improved PFS (HR 0.5, 95% CI 0.2-0.9, p=0.03) and OS (HR 0.5, 95% CI 0.3-0.9 p=0.04) as compared to sons. Relapse rate was highest with son-to-mother (HR 1.7, 95% CI 1.02-2.7, p=0.04). PB graft was associated with a significantly higher risk of cGVHD (HR 3.1, 95% CI 1.5-6.4, p=0.003). High/very high DRI was associated with a high risk of relapse (HR 2.4, 95% CI 1.5-3.9, p<0.001). Patient age >50 yrs had high NRM (HR 2.03, 95% CI 1.1-3.7, p=0.02), poor PFS (HR 1.5, 95% CI 1.02-2.3, p=0.04) and OS (HR 1.6, 95% CI 1-2.5, p=0.05). There was no significant impact of specific HLA mismatches on any of the outcomes. Having 3 class II HLA (vs <3) mismatches was associated with a high risk of cGVHD (HR 3.3, 95% CI 1.3-8.7, p=0.01), with no impact on survival. Conclusion: Among child haplo donors, our data suggest that female donors do not result in any inferior outcomes as compared to male donors. A daughter may even be a preferred donor for patients with high/very-high DRI as it conferred survival benefit as compared to a son donor. This may partly be related to a higher risk of relapse seen in son donor to mother recipient. Also, certain HLA mismatches (e.g. B-leader), which have prognostic implications in haplo HCT in general, did not appear to be of significance when accounted for donor relationship and age in patients with a child donor. Further large-scale studies are needed to comprehend these complex immunobiological relationships. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

S1202 Drug-Induced Liver Injury (DILI) Ascribed to Non-Steroidal Anti-inflammatory Drugs (NSAIDs) in the USA: An Update With Genetic Correlations From the U.S. Drug-Induced Liver Injury Network (DILIN)

Introduction: NSAIDs are widely used throughout the world, mainly for management of chronic inflammatory and painful conditions. NSAIDs rarely cause idiosyncratic, non-dose dependent liver injury. Recent evidence from the US DILIN, as well as elsewhere, implicates host immune responses as central to pathogenesis of such idiosyncratic DILI. Previously, we reported the US DILIN experience with NSAID DILI for 2004-2013.1 Aim: To update our clinical experience and report on HLA and other genetic factors recently described as important in idiosyncratic DILI. Methods: The US DILIN, begun in 2004; is comprised of clinical sites [currently 7 in number], a data coordinating center, and the NIDDK. We enroll subjects with suspected DILI and follow them for at least 6 months.2 We adjudicate causality both with RUCAM, and RECAM3 and by a Delphic approach4 and grade severity from mild to fatal or requiring liver transplant.5 Between Sep 2004 and Mar 2022, we enrolled 2,626 subjects and adjudicated causality at 6 months in 2,498. Following adjudication, we identified 55 [41 (75%) women] as definitely [ >95%], highly likely [75-95%], or probably [51-74% likely] due to NSAIDs. Results: Diclofenac was the causative drug in 29/55 [53%] of cases, followed by celecoxib [7], ibuprofen [5], etodolac and meloxicam [4 each]. Median latency was 51 d. With the notable exceptions of meloxicam and oxaprozin [n=2], the type of liver injury was hepatocellular with median R 15-25. 4 subjects died within 6 mo of onset, and 2 others [1 each due to diclofenac and celecoxib] required liver transplants. 7 had chronic DILI at 6+ mo. HLA DRB1*03:01 was more frequent in those with NSAID DILI than in matched controls, and 6/10 had the ancestral AI extended haplotype. The likelihood of carrying the DRB1*04:03 allele increased with causality score confidence and with more severe DILI [p =0.006]. Conclusion: NSAID DILI is relatively rare in the US. The most common cause is diclofenac, which, if prescribed, should carry with it special warnings of risk and close observation, as in the package insert. The increased frequencies of HLA DRB1*03:01, an HLA type known to be associated with SLE and other auto-immune disorders, and the extended ancestral AI haplotype, suggests that immune-mediated responses are of central importance in pathogenesis.

Stem cells perspective in cure and management of diabetic retinopathy

Diabetic retinopathy is the trending issue of the vision loss worldwide that occurs due to mismanagement of glycemic level of the diabetic patients. In diabetic retinopathy neurons and capillaries, which are associated with retina, start to damage that result in alteration in the vision function of retina. Long term effective strategy for diabetic retinopathy has not been proposed yet but the stem cells can make it possible to prevent or cure diabetic retinopathy. Stem cells have the potential of repairing and replacement of damaged or defected retinal cells. Different types of stem cells like induced pluripotent stem cells, mesenchymal stem cells, some other factors like CD34+ cells, HLA factors etc have a significant role in the treatment of diabetic retinopathy. In this review, other than the role of stem cells, we have discussed the management and screening of diabetic retinopathy. Management and screening, are the parts of the strategy to reduce the risk of diabetic retinopathy that act like the tools to treat diabetic retinopathy. As stem cells are the most feasible source of treatment of diabetic retinopathy. Management and screening of diabetic retinopathy at early stage could be helpful in treatment even when the patient doesn’t show symptoms. The stem cell therapy in diabetic retinopathy offers a long lasting treatment option. Keywords: CD34+ cells; Diabetic retinopathy; HLA factors; Induced pluripotent stem cells; Mesenchymal stem cells http://dx.doi.org/10.19045/bspab.2021.100147

HLA informs risk predictions after haploidentical stem cell transplantation with posttransplantation cyclophosphamide

AbstractHematopoietic cell transplantation from HLA-haploidentical related donors is increasingly used to treat hematologic cancers; however, characteristics of the optimal haploidentical donor have not been established. We studied the role of donor HLA mismatching in graft-versus-host disease (GVHD), disease recurrence, and survival after haploidentical donor transplantation with posttransplantation cyclophosphamide (PTCy) for 1434 acute leukemia or myelodysplastic syndrome patients reported to the Center for International Blood and Marrow Transplant Research. The impact of mismatching in the graft-versus-host vector for HLA-A, -B, -C, -DRB1, and -DQB1 alleles, the HLA-B leader, and HLA-DPB1 T-cell epitope (TCE) were studied using multivariable regression methods. Outcome was associated with HLA (mis)matches at individual loci rather than the total number of HLA mismatches. HLA-DRB1 mismatches were associated with lower risk of disease recurrence. HLA-DRB1 mismatching with HLA-DQB1 matching correlated with improved disease-free survival. HLA-B leader matching and HLA-DPB1 TCE-nonpermissive mismatching were each associated with improved overall survival. HLA-C matching lowered chronic GVHD risk, and the level of HLA-C expression correlated with transplant-related mortality. Matching status at the HLA-B leader and HLA-DRB1, -DQB1, and -DPB1 predicted disease-free survival, as did patient and donor cytomegalovirus serostatus, patient age, and comorbidity index. A web-based tool was developed to facilitate selection of the best haploidentical-related donor by calculating disease-free survival based on these characteristics. In conclusion, HLA factors influence the success of haploidentical transplantation with PTCy. HLA-DRB1 and -DPB1 mismatching and HLA-C, -B leader, and -DQB1 matching are favorable. Consideration of HLA factors may help to optimize the selection of haploidentical related donors.

Role of pharmacogenomics in T-cell hypersensitivity drug reactions.

An update of the pharmacogenetic risk factors associated with T-cell-mediated delayed hypersensitivity reactions. Recent HLA associations relevant to our understanding of immunopathogenesis and clinical practice include HLA-B∗13:01 with co-trimoxazole-induced SCAR, and HLA-A∗32:01 with vancomycin-DRESS, for which an extended HLA class II haplotype is implicated in glycopeptide antibiotic cross-reactivity. Hypoactive variants of ERAP1, an enzyme-trimming peptide prior to HLA loading, are now associated with protection from abacavir-hypersensitivity in HLA-B∗57:01+ patients, and single-cell sequencing has defined the skin-restricted expansion of a single, public and drug-reactive dominant TCR across patients with HLA-B∗15:02-restricted carbamazepine-induced SJS/TEN. More recent strategies for the use of HLA and other risk factors may include risk-stratification, early diagnosis, and diagnosis in addition to screening. HLA is necessary but insufficient as a risk factor for the development of most T-cell-mediated reactions. Newly emerged genetic and ecological risk factors, combined with HLA-restricted response, align with underlying immunopathogenesis and drive towards enhanced strategies to improve positive-predictive and negative-predictive values. With large population-matched cohorts, genetic studies typically focus on populations that have been readily accessible to research studies, but it is now imperative to address similar risk in globally relevant and understudied populations.

Humoral Risk Factors Associated to Allograft Dysfunction after Lung Transplantation: The Alert of Non-HLA Auto Antibody and HLA-Donor Specific Antibody (DSA) with Non-DSA HLA Antibody

<h3>Purpose</h3> Growing evidence has indicated the negative impact of non-HLA auto antibody (NHAuAb) on organ transplantation. Donor specific antibody (DSA) after lung transplantation (LuT) has been observed frequently with de novo Non-DSA (dN-DSA) HLA antibody. This study investigates the deleterious role of post-LuT NHAuAb and dN-DSA synergism to DSA in allograft damage. <h3>Methods</h3> We retrospectively analyzed NHAuAb and de novo DSA (dDSA)/dN-DSA data collected from the recipients who underwent LuT during 2012-2016. NHAuAbs were detected using LABScreen™ Autoantibody (>95% non-sensitized subjects as cut-off). HLA antibody was tested by LABScreen™ SAB (MFI≥ 1000 as cut-off). Clinical Antibody Mediated Rejection (cAMR, with acute graft dysfunction) and Chronic Lung Allograft Dysfunction (CLAD) were assessed for LuT outcomes. <h3>Results</h3> CXCL9, AURKA, REG3A, IFNγ, FLRT2, GDNF, HNRNPK, CXCL10, PLA2R, and Collagen IV detected from 111 patients' sera drawn at DSA peak phase showed significant association to total AMR, but only FLRT2 (P<0.001), GDNF, and CXCL10 (P<0.05) were remarkably correlated to cAMR (Table 1a). Preformed & persistent LG3, PECR, PKC-Z (P<0.001) and de novo ENO1, GAPDH, Lamin-B, TubulinA1B (p<0.05) identified from 113 patients' sera drawn around CLAD time, demonstrated strong correlation to the occurrence of CLAD (Table 1b). Patients with dDSA & dN-DSA had significantly higher incidence of cAMR than the patients with only dDSA (p<0.001, Table 1c). <h3>Conclusion</h3> Distinct clinical phases presented specific NHAuAb profiles. Multiple NHAuAbs, especially LG3, PKC-Z, and PECR which were preformed & persistent, promoted chronic graft dysfunction. HLA-dDSA augmented by dN-DSA (most likely through shared targeting epitopes) and NHAuAbs of FLRT2, GDNF, and CXCL10 were related to acute graft injury. These HLA and non-HLA humoral risk factors warrant timely enhanced immune therapy to prevent final allograft failure.

First-appearing islet autoantibodies for type 1 diabetes in young children: maternal life events during pregnancy and the child's genetic risk.

Psychological stress has long been considered a possible trigger of type 1 diabetes, although prospective studies examining the link between psychological stress or life events during pregnancy and the child's type 1 diabetes risk are rare. The objective of this study was to examine the association between life events during pregnancy and first-appearing islet autoantibodies (IA) in young children, conditioned by the child's type 1 diabetes-related genetic risk. The IA status of 7317 genetically at-risk The Environmental Determinants of Diabetes in the Young (TEDDY) participants was assessed every 3months from 3months to 4years, and bi-annually thereafter. Reports of major life events during pregnancy were collected at study inception when the child was 3months of age and placed into one of six categories. Life events during pregnancy were examined for association with first-appearing insulin (IAA) (N = 222) or GAD (GADA) (N = 209) autoantibodies in the child until 6years of age using proportional hazard models. Relative excess risk due to interaction (RERI) by the child's HLA-DR and SNP profile was estimated. Overall, 65% of mothers reported a life event during pregnancy; disease/injury (25%), serious interpersonal (28%) and job-related (25%) life events were most common. The association of life events during pregnancy differed between IAA and GADA as the first-appearing autoantibody. Serious interpersonal life events correlated with increased risk of GADA-first only in HLA-DR3 children with the BACH2-T allele (HR 2.28, p < 0.0001), an additive interaction (RERI 1.87, p = 0.0004). Job-related life events were also associated with increased risk of GADA-first among HLA-DR3/4 children (HR 1.53, p = 0.04) independent of serious interpersonal life events (HR 1.90, p = 0.002), an additive interaction (RERI 1.19, p = 0.004). Job-related life events correlated with reduced risk of IAA-first (HR 0.55, p = 0.004), particularly in children with the BTNL2-GG allele (HR 0.48; 95% CI 0.31, 0.76). Specific life events during pregnancy are differentially related to IAA vs GADA as first-appearing IA and interact with different HLA and non-HLA genetic factors, supporting the concept of different endotypes underlying type 1 diabetes. However, the mechanisms underlying these associations remain to be discovered. Life events may be markers for other yet-to-be-identified factors important to the development of first-appearing IA.

Improving Donor Selection for Haploidentical Stem Cell Transplantation with Post-Transplant Cyclophosphamide through Selective HLA-Mis/Matching

Background HLA-haploidentical (haplo) blood or marrow transplantation (BMT) with post-transplantation cyclophosphamide (PTCy) is widely used, but few factors that inform donor selection have been identified. Based on prior observations for HLA-B leader (EW Petersdorf et al. Lancet Haematol 2020), HLA-DRB1 (YL Kasamon et al. BBMT 2010), and HLA-DPB1 (SR Solomon et al. BBMT 2018), we hypothesized that mismatching at individual HLA loci may influence BMT outcomes, but single and additive HLA gene effects have not been evaluated systematically in the context of haploBMT with PTCy. Methods The Center for International Blood and Marrow Transplant Research (CIBMTR) identified 1,434 patients who underwent T-cell-replete haploBMT with PTCy for acute leukemia or myelodysplastic syndrome (MDS) between 2008-2017. Multivariable models assessed transplant outcomes associated with 3 HLA-factors: (1) B-leader dimorphism (MM, MT, TT) matching; (2) HLA-DRB1 mismatching in the graft-versus-host (GVH) direction; and (3) nonpermissive HLA-DPB1 mismatching in the GVH direction using the T-cell epitope-3 model, which classifies HLA-DPB1 mismatches into permissive or non-permissive. All final models contained the HLA factors and adjusted for other significant clinical covariates at p&amp;lt;.05 in univariate analysis. P-values were not adjusted for multiple testing. Results Diagnoses were 58% AML, 23% ALL, 19% MDS. 22% of AML patients were in advanced disease stage (relevant analyses were stratified for disease stage for both acute leukemia and MDS). Median recipient age was 54 (range 1-78) years. Median follow up among survivors was 12 (range 2-119) months. Marrow was the graft source in 43% of recipients. Myeloablative conditioning was used in 45% of recipients. Fifty percent of recipients had hematopoietic cell transplantation-comorbidity index (HCT-CI) scores of ≥3. HLA-DP typing was missing in 52% of cases and thus all models had a "missing" category for HLA-DP. Mismatching in the GVH direction at HLA-A, HLA-C, or HLA-DQ was not associated with study outcomes [overall survival (OS), disease-free survival (DFS), relapse, nonrelapse mortality (NRM), or grade II-IV acute, grade III-IV acute, or chronic graft-versus-host disease (gr2-4a or cGVHD)]. When compared to leader-matched patients, HLA-B leader-mismatching was associated with worse OS and DFS (hazard ratio [HR] 1.25 [95% CI, 1.09 to 1.44]; P=.002, and HR 1.18 [95% CI, 1.03 to 1.34]; P=.01, respectively), and higher risk of NRM (HR 1.38 [95% CI, 1.10 to 1.74]; P=.005), but was not associated gr2-4a or cGVHD, or relapse. In contrast, when compared to matching at HLA-DRB1, the presence of any GVH direction mismatch at HLA-DRB1 was associated with improved DFS (HR 0.80 [95% CI, 0.68 to 0.94]; P=.007) and lower risk of relapse (HR 0.69 [95% CI, 0.56 to 0.86]; P=.0008), but with no effect on OS, gr2-4a or cGVHD, or NRM. Similarly, any nonpermissive GVH mismatching at HLA-DPB1 was also associated with improved DFS (HR 0.72 [95% CI, 0.55-0.94], p=.015) and OS (HR 0.59 [95% CI, 0.43-0.82], p=.002), with a tendency towards lower relapse (HR 0.75 [95% CI, 0.54-1.05], p=.09), but with no effect on gr2-4a or cGVHD, or NRM. When combining the effects of leader matching at HLA-B and mismatching at HLA-DRB1 there was an additive improvement in both DFS and OS (Figure 1 A and B) with significantly lower NRM (p=0.03) and relapse (p=0.008) when compared to other groups. Within this unselected large cohort, favorable haplo donors based on B-leader matching and HLA-DRB1 mismatching were used for 48.5% of recipients and had improved DFS (HR 0.68 [95% CI, 0.52 to 0.88], p=.004) when compared to B-leader mismatched and HLA-DRB1 matched pairs, suggesting that with intentional selection of donors based on these factors, even more could receive a favorable combination. Conclusion HLA-B leader mismatching is a risk factor for NRM and worse OS and DFS, whereas either HLA-DRB1 or nonpermissive HLA-DPB1 mismatch is associated with reduced relapse and improved DFS, after haploBMT with PTCy. PTCy dissociates the graft-versus-leukemia effect of HLA-DRB1 and nonpermissive HLA-DPB1 mismatching from GVHD. The best outcomes after haploBMT with PTCy are seen when a donor is HLA-B leader matched and HLA-DRB1 mismatched. When there is more than one potential haplo donor for an acute leukemia or MDS patient, selection based on HLA considerations may improve DFS and OS. Figure Disclosures Shaw: Orca Bio: Consultancy. Lee:Takeda: Research Funding; AstraZeneca: Research Funding; Novartis: Research Funding; Incyte: Consultancy, Research Funding; Syndax: Research Funding; Pfizer: Consultancy, Research Funding; Amgen: Research Funding; Kadmon: Research Funding.

Humoral Risk Factors Associated to Allograft Dysfunction after Lung Transplantation: The Alert of Non-HLA Auto Antibody and HLA Donor Specific Antibody (DSA) with Non-DSA HLA Antibody

Growing evidence has indicated the negative impact of non-HLA auto antibody (NHAuAb) on organ transplantation. Donor specific antibody (DSA) after lung transplantation (LuT) has been observed frequently with de novo Non-DSA (dN-DSA) HLA antibody. This study investigates the deleterious role of post-LuT NHAuAb and dN-DSA synergism to DSA in allograft damage. We retrospectively analyzed NHAuAb and de novo DSA (dDSA)/dN-DSA data collected from recipients who underwent LuT during 2012-2016. NHAuAbs were detected using LABScreen™ Autoantibody (>95% non-sensitized subjects as cut-off). HLA antibody was tested by LABScreen™ SAB (MFI≥ 1000 as cut-off). Clinical Antibody Mediated Rejection (cAMR, with acute graft dysfunction) and Chronic Lung Allograft Dysfunction (CLAD) were assessed for LuT outcomes. CXCL9, AURKA, REG3A, IFNγ, FLRT2, GDNF, HNRNPK, CXCL10, PLA2R, and Collagen IV detected from 111 patients' sera drawn at DSA peak phase showed significant association to total AMR, but only FLRT2 (P<0.001), GDNF, and CXCL10 (P<0.05) were remarkably correlated to cAMR (Table 1a). Preformed & persistent LG3, PECR, PKC-Z (P<0.001) and de novo ENO1, GAPDH, Lamin-B, TubulinA1B (p<0.05) identified from 113 patients' sera drawn around CLAD time, demonstrated strong correlation to the occurrence of CLAD (Table 1b). Patients with dDSA & dN-DSA had significantly higher incidence of cAMR than the patients with only dDSA (p<0.001, Table 1c). Distinct clinical phases presented specific NHAuAb profiles. Multiple NHAuAbs, especially LG3, PKC-Z, and PECR, which were preformed and persistent, promoted chronic graft dysfunction. HLA-dDSA augmented by dN-DSA (most likely due to shared targeting epitopes) and NHAuAbs of FLRT2, GDNF, and CXCL10 were related to acute graft injury. These HLA and non-HLA humoral risk factors warrant timely enhanced immune therapy to prevent final allograft failure.

P047 A cold case: When single antigen beads assay do not respond

Case history: We evaluated a live donor (D1) and recipient (P1) pair for potential kidney donation however their flow crossmatches (FXM) continuously result in B-cell positive. P1 was tested negative by single antigen beads and no donor specific antibody (DSA) was evident. Patient has been transfused once in 2014 and treated with adalimumab for ankylosing spondylitis in the past. Methods: Autologous FXM of D1 was conducted. A series of FXM with surrogate donors was conducted. Supplemental single antigen beads, FlowPRA beads and Luminex-based mixed screening beads were also conducted but results are questionable. Results: After the first allo FXM, a repeat was done to rule out B cell positive FXM whether it was reproducible. Since patient was screened negative by single antigen beads assay and supplemental beads, absence of DSA could not explain why B cell FXM can be positive. When patient serum subject to two other surrogate donors (D2 “O” and D3 “A”) interestingly B cell FXM has become negative. To rule out blood type issue and non–HLA factors, autologous FXM of D1 and allo-FXM with zero PRA serum (P2 “A”), and with positive PRA serum (absence of DSA, P3 “A”) were performed and all were found negative, but remained positive with diluted serum of P1. Patient P1 was tested again in 3 months however the same result remains. The final FXM was then focused on testing with surrogate donors (D4 and D5) who carry the same class II antigens as D1. The result became positive with D5. Although no clear evidence can confirm the antibody to DR11 to be allele specific, the collective results infer that suspected DSA DR11 is not distinguishable by FlowPRA screening beads and mixed beads and not detectable by single antigen and supplemental beads. Conclusion: This is the first case in our experience to discover such a situation with “cold bead” or specificity-unproven DSA. Transplantation is not recommended. Correlation between different assays and diligent testing to clarify unreasonable positive FXM is very important especially in cases of autoimmune disease.

Identification of risk epitope mismatches associated with de novo donor-specific HLA antibody development in cardiothoracic transplantation.

The development of de novo donor-specific HLA antibodies (dnDSA) after transplantation is associated with graft failure, mortality, and cost. There is no effective therapeutic intervention to prevent dnDSA or ameliorate associated injury. The aims of this study were to identify specific HLA factors associated with dnDSA development and to propose primary prevention strategies that could reduce the incidence of dnDSA without prohibitively limiting access to transplant. The investigation cohort included heart transplant recipients from 2008 to 2015 (n=265). HLA typing was performed and HLA antibody testing was undertaken before and after transplantation. HLAMatchmaker analysis was performed for persistent dnDSA to identify potentially more immunogenic eplet differences. Validation was performed in recipients of lung transplants from 2008 to 2013 (n=433). The majority of recipients with dnDSA had antibodies to identical eplet positions on DQ2 and DQ7. A high-risk epitope mismatch (found in DQA1*05+ DQB1*02/DQB1*03:01(7)) was associated with a 4.2- and 4.9-fold increased risk of dnDSA in heart and lung recipients respectively. HLA electrostatic potential modeling provided a plausible explanation for this observed immunogenicity. A theoretical allocation algorithm avoiding high-risk epitope mismatches was generated and predicted to reduce dnDSA by up to 72% without additional testing, eplet analysis, or cost.

Genome-Wide Analysis to Identify HLA Factors Potentially Associated With Severe Dengue.

The pathogenesis of dengue hemorrhagic fever (DHF), following dengue virus (DENV) infection, is a complex and poorly understood phenomenon. In view of the clinical need of identifying patients with higher likelihood of developing this severe outcome, we undertook a comparative genome-wide association analysis of epitope variants from sequences available in the ViPR database that have been reported to be differentially related to dengue fever and DHF. Having enumerated the incriminated epitope variants, we determined the corresponding HLA alleles in the context of which DENV infection could potentially precipitate DHF. Our analysis considered the development of DHF in three different perspectives: (a) as a consequence of primary DENV infection, (b) following secondary DENV infection with a heterologous serotype, (c) as a result of DENV infection following infection with related flaviviruses like Zika virus, Japanese Encephalitis virus, West Nile virus, etc. Subject to experimental validation, these viral and host markers would be valuable in triaging DENV-infected patients for closer supervision owing to the relatively higher risk of poor prognostic outcome and also for the judicious allocation of scarce institutional resources during large outbreaks.

The effect of HLA allele and haplotype polymorphisms on donor matching in hematopoietic stem cell transplantation – Croatian experience

The knowledge of HLA characteristics of a patient’s population helps to predict the probability of finding a MUD.The study included 170 transplanted patients for whom a search for a MUD in BMDW was performed and a sample of 4000 volunteer unrelated donors from the Croatian Bone Marrow Donor Registry (CBMDR). Patients and their MUDs were typed for HLA-A, -B, -C, -DRB1, and -DQB1 loci using PCR-SSO and PCR-SSP methods while donors were typed for HLA-A, -B, -C, and -DRB1 loci using the PCR-SSO method.A comparison of allele frequencies at tested HLA loci between patients and donors from CBMDR did not reveal significant differences. The majority of patients (117, 68.8%) had a 10/10 MUD, 45 (26.5%) patients had a 9/10 MUD and eight (4.7%) patients had an 8/10 MUD. The highest number of mismatches (MM) was present at HLA-DRB1 (19; 31.1%). The presence of DRB1*11 and DRB1*04 allelic groups among patients caused allelic MMs at HLA-DRB1 in most cases. The presence of an infrequent HLA-B∼C haplotype resulted in the HLA-C MM at antigen level in the majority of cases.The present study clarified HLA factors that cause difficulties in searching for a 10/10 MUD for Croatian patients.

OR36 Defining KIR and HLA class I alleles at highest resolution using next generation sequencing

Aim Combinatorial diversity of KIR and HLA class I alleles directly affects NK cell activity and impacts the outcome of human immune responses to infections, and success in reproduction and transplantation. Therefore it is important to identify genetic variation in these highly polymorphic genes at high resolution. Here we have used our high throughput capture/NGS method to target KIR and HLA class I genes. Methods Libraries were prepared using fragmented genomic DNA samples from 1000 European individuals, 97 IHWG cell lines and 31 family trios from West Africa. After capture of fragments with oligonucleotide probes, the entire KIR locus and HLA class I genes were sequenced to high depth (100×) using Illumina paired-end technology. We also developed a bioinformatics pipeline (PING: Pushing Immunogenetics to the Next Generation) specifically to extract and analyze the KIR-specific reads from any NGS data source. PING attributes sequencing reads to specific KIR genes, determines their copy number by read depth and virtual sequence probes, and then calls high-resolution genotypes. PING also returns information on newly-identified SNPs and recombinant alleles. PING is available as an R package at https://github.com/ . Results The method was validated using data from the 97 IHWG cell lines. KIR gene copy numbers were independently verified by complete correlation with real time PCR, and the allele calls using pyrosequencing and Sanger sequencing. We determined the composition of all the KIR haplotypes represented in the 97 IHWG cells, which are available for reference. PING was further validated by analyzing the 1000 genomes data set for 3DL1/S1 and 3DL2, where we identified and validated 100 novel alleles. This analysis of just two KIR genes doubled the number of known 3DL2 alleles, and showed that 22% of the 1000 Genomes subjects have a novel allele or a structural variant. Subsequently in analyzing the European and African we find few novel HLA class I alleles, but in contrast we find one novel KIR allele per ten individuals. Conclusions The KIR locus is likely to be as diverse as HLA. The method we describe is suited to the large-scale analyses that are needed for characterizing human populations, matching transplant donors with recipients, and defining the precise HLA and KIR factors associated with disease.