Noninherited Maternal Antigens Research Articles

Regulatory T cell homing and activation is a signature of neonatal sepsis.

Regulatory T cells (Treg) play a prominent role in utero tolerating non-inherited maternal antigens and in regulating immune responses against pathogens at birth. This study investigates Treg immunity in newborns in West Africa, where sepsis remains a major public health problem. Treg phenotypes on neonates subgroups with early-onset sepsis (EOS), presumed sepsis, and healthy newborn with and without prenatal risk factors were evaluated. Treg phenotypes varied according to prenatal conditions, with increase in Treg frequency and Foxp3 expression in healthy newborns with prenatal risk factors compared to those with none risk. Compared to healthy newborns with prenatal risk factors, EOS neonates had a significantly reduced frequency of Treg and Foxp3 expression. In the Treg pool, higher frequency of activated Treg was observed in EOS neonates, suggesting an in-utero activation upstream of the sepsis onset. Their migration to the infection site may explain the reduced frequency of circulating Integrin α4β1+ Treg suggestive of homing to the endothelial tissue. EOS neonates show increases expression of CTLA-4, PD-1 and CD39 on Treg, which negatively regulate the activation of effector T cells (Teff) corroborating by the lower frequency of Teff in EOS neonates. The higher frequency of CD39+ Treg and the lower frequency of integrinα4β1+ Treg in EOS non-survivor suggests that Treg exhaustement and endothelial homing are associated with outcome severity. Neonates developing EOS are born with an altered Treg phenotypic profile. Treg expression of CTLA-4, PD-1, CD39, and integrinα4β1 cell markers can be considered as early warning or diagnostic markers of EOS.

Reproductive outcomes after pregnancy-induced displacement of preexisting microchimeric cells.

Pregnancy confers partner-specific protection against complications in future pregnancy that parallel persistence of fetal microchimeric cells (FMcs) in mothers after parturition. We show that preexisting FMcs become displaced by new FMcs during pregnancy and that FMc tonic stimulation is essential for expansion of protective fetal-specific forkhead box P3 (FOXP3)-positive regulatory T cells (Treg cells). Maternal microchimeric cells and accumulation of Treg cells with noninherited maternal antigen (NIMA) specificity are similarly overturned in daughters after pregnancy, highlighting a fixed microchimeric cell niche. Whereas NIMA-specific tolerance is functionally erased by pregnancy, partner-specific resiliency against pregnancy complications persists in mothers despite paternity changes in intervening pregnancy. Persistent fetal tolerance reflects FOXP3 expression plasticity, which allows mothers to more durably remember their babies, whereas daughters forget their mothers with new pregnancy-imprinted immunological memories.

The Proportion of Recent Thymic Emigrant Lymphocytes in Breastfed and Formula Fed Term Neonates

Recent thymic emigrants (RTEs) represent a distinct T cell subset characterized by a tolerance-prone status. We have recently demonstrated that the proportion of regulatory T cells (Tregs) is nearly two-fold higher in exclusively breastfed compared with exclusively formula-fed neonates. However, it has been unknown whether the type of milk is also associated with the proportion of the RTE cell compartment. Cord blood (CB) and, at three weeks of age, peripheral venous blood samples were collected from 19 healthy-term neonates. A maternal blood sample was also taken. The proportion of RTEs, naïve CD4 cells, naïve RTEs, and Tregs was analyzed by flow cytometry in blood samples. RTE cell proportions were comparable between CB and 3 weeks. At both time points, there was no difference in the proportion of naïve CD4 cells, RTE CD4 cells, and naïve RTE CD4 cells between the feeding groups. The fold change of RTE cells between birth and three weeks of life was highest in mixed-fed babies. Since RTE counts were comparable across the feeding groups at birth, this most likely reflects a postnatal upregulation, to which the dual antigenic exposure to both non-inherited maternal antigens via breastmilk, as well as to other environmental antigens in formula milk, may contribute.

HLA B-Leader Mismatch Is Associated with Poor Outcomes in NIMA/NIPA Mismatched Haploidentical Sibling Donor HCT

Background: Sibling haplo donors can be broadly categorized as non-inherited maternal (NIMA) or paternal (NIPA) antigen mismatched based on the non-shared haplotype with the recipient. Older studies with non-PTCy prophylaxis suggested a benefit of NIMA-mismatched over NIPA-mismatched donors, but the same has not been studied with PTCy prophylaxis, especially in the context of increasing recognition of the impact of specific loci HLA-mismatches in haplo HCT, such as the B-leader, which is a leader peptide that is preferentially bound by HLA-E, the ligand for natural killer (NK) receptor NKG2. Objective: To compare the outcomes of NIMA-vs NIPA-mismatched haplo sibling donors and specific loci HLA-mismatches in the setting of T-cell replete HCT with PTCy prophylaxis. Results: We included 57 patients: 29 were NIMA-mismatched and 28 were NIPA-mismatched. Median age at HCT (31 yrs vs 37 yrs, p=0.1) and donor age (32 yrs vs 41 yrs, p=0.1) were similar in both groups. Most received RIC (72% vs 68%, p=0.5), BM graft (79% vs 82%, p=0.8), had HCT-CI >3 (55% vs 54%, p=0.9) and low/intermediate DRI (62% vs 54%, p=0.4) and were ABO matched (65% vs 71%, p=0.8) with the donor. There was a significantly higher proportion of female-donor to male-recipients in the NIMA- than NIPA-mismatched group (55% vs 21%, p=0.005). Specific HLA-mismatches were similar in both groups: B-leader (52% vs 32%, p=0.1), DRB1 (96% each), DQB1 (90% vs 86%, p=0.5), DPB1 (76% vs 79%, p=0.9). The median follow-up was 38 vs 13 months. There were no graft failures, and the median time to engraftment was similar (18 vs 19 days, p=0.3). The cumulative incidence of grade II-IV aGVHD was 31% vs 58%, p=0.04; with no differences in grade III-IV aGVHD (10% vs 11%, p=0.9), cGVHD (11% vs 13%, p=0.9); NRM (28% vs 33%, p=0.9), relapse (21% vs 11%, p=0.4), or OS (54% vs 55%, p=0.8) in NIMA-vs NIPA-mismatched, respectively. In multivariate analysis, NIMA-mismatch (HR 0.1, 95% CI 0.02-0.6, p=0.01 in females) and HLA-A mismatch (HR 0.2, 95% CI 0.1-0.6, p=0.005) were associated with significantly lower risk of grade II-IV aGVHD, while age at HCT >50 yr was high risk for grade II-IV aGVHD (HR 2.7, 95% CI 1.1-6.9, p=0.04). No factor predicted grade III-IV aGVHD, cGVHD or relapse, likely related to a small number of events. B-leader mismatch was associated with high NRM (HR 3.8, 95% CI 1.04-13, p=0.04), poor PFS (HR 2.7, 95% CI 1.1-6.7, p=0.03), and a trend for lower OS (HR 2.4, 95% CI 0.9-6.3, p=0.06). High/very-high DRI was associated with high NRM (HR 4.4, 95% CI 1.5-13, p=0.008) and poor OS (HR 2.6, 95% CI 1-6.6, p=0.05). HCT-CI >3 (HR 2.9, 95% CI 0.9-8.8, p=0.05) was associated with poor OS. Neither NIMA-mismatch nor any other independent HLA-locus mismatches (except B-leader) had an impact on NRM, relapse, PFS, or OS. Conclusion: Among sibling haplo donors, a B-leader matched donor should be prioritized whenever possible. When multiple B-leader matched donors are available, considering the sample size limitations, our data suggest that a donor mismatched at A-locus (lower aGVHD) and/or a NIMA-mismatched donor (lower aGVHD in females) could be selected. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Cross-decoration of dendritic cells by non-inherited maternal antigen-containing extracellular vesicles: Potential mechanism for PD-L1-based tolerance in cord blood and organ transplantation

Exposure to non-inherited maternal antigens (NIMA) during the fetal period induces lifelong split tolerance to grafts expressing these allo-antigens. In adult mice, the production of extracellular vesicles (EVs) from maternal microchimeric cells causes cross-decoration (XD) of offspring dendritic cells (DC) with NIMA and upregulation of PD-L1, contributing to NIMA tolerance. To see how this may apply to humans, we tested NIMA acquisition by fetal DCS in human cord blood. The average percentage of NIMA-XD among total DCs was 2.6% for myeloid and 4.5% for Plasmacytoid DC. These cells showed higher PD-L1 expression than their non-XD counterparts (mDC: p = .0016; pDC: p = .024). We detected CD9+ EVs bearing NIMA and PD-L1 in cord blood. To determine if this immune regulatory mechanism persists beyond the pregnancy, we analyzed NIMA-expressing kidney and liver transplant recipients. We found donor antigen XD DCs in peripheral blood and graft-infiltrating DCs. As in cord blood, the pattern of donor antigen expression was punctate, and PD-L1 expression was upregulated, likely due to both protein and miRNA acquired from EV. Our findings support a mechanism for split tolerance to NIMAs that develops during pregnancy and is recapitulated in adult transplant recipients.

Anneke Brand (1946-2021).

Anneke Brand, Professor in Transfusion Medicine, passed away on Sunday, 21 November 2021, at the age of 75. She was a pioneer in both the immunological and clinical aspects of blood transfusion. She has played a pivotal role in the development of the Dutch Cord Blood Bank. During her entire career, she was dedicated to inspiring many researchers and clinicians alike in the field of transfusion medicine and haematology. Her ability to question and challenge scientific findings, as well as many social issues, is unequalled. Anneke was born on 7 June 1946 in The Hague, the Netherlands. In 1973, she obtained her medical degree from the Free University Amsterdam and was accepted for a PhD project at the Department of Immunohaematology and Blood Bank of the Academic Hospital Leiden under the wings of Prof. Jon van Rood and Dr George Eernisse. In this project, she started working on the management of patients refractory to platelet transfusions, including antibody detection and donor selection. In those days, many leukaemia patients suffered from severe bleeding complications and presented with unexplained severe transfusion reactions and markedly reduced post-transfusion increments. In the laboratory of the Immunohaematology Department, important aspects of the human leukocyte antigen (HLA) class type I system were unravelled and the first sibling bone marrow transplants for severe combined immunodeficiency and aplastic anaemia patients were performed. Laboratory tests to detect HLA antibodies were developed. In 1978 she defended her thesis ‘Platelet Supportive Care’, and meanwhile learned all aspects of blood-banking. After this, she started her training in internal medicine in Haarlem, followed by her specialization in haematology at the Leiden Academic Hospital. As a medical specialist, in 1984 she returned to the Blood Bank and Haemapheresis Department, combining patient care and clinical research, investigating the role of leukocytes on clinical transfusion outcomes in various disorders, from colorectal cancer surgery to erythrocyte alloimmunization. Her research led to the adoption of leukoreduction to diminish alloimmunization as well as other adverse transfusion reactions. After a sabbatical in Paris in the laboratory of Prof. Michel Kazatchkine working on anti-idiotypic antibodies in intravenous immunoglobulins, in 1988 she succeeded George Eernisse as Medical Director of the Red Cross Leiden and the Blood Bank of the Leiden University Hospital. After the AIDS drama, good manufacturing practice became mandatory and regional Dutch blood banks merged with neighbouring blood banks. Over a period of 10 years, all Dutch Red Cross blood banks gradually merged with the Dutch Laboratory of the Red Cross to form one national organization: Sanquin. In 1994, together with Fred Falkenburg, she established the Dutch Cord Blood Bank, a joint effort between the Leiden University Medical Centre and the Red Cross Blood Bank. In 1995, she joined the Royal College of Pathology, and in 1999 she became Professor of Internal Medicine with assignment to Transfusion Medicine. In that period, she started researching the optimal conditions for the storage and expansion of cord blood for transplantation as well as exploring the possibility of using cord blood to produce red blood cells for transfusion. From 2000 till her ‘age-enforced’ retirement in 2011, she was the head of clinical research at Sanquin Blood Bank Southwest. In this period, several clinical trials were successfully conducted, including studies regarding peri-operative blood management strategies as well as several clinical platelet transfusion trials. After her retirement, she remained active in many fields, including the board of the European Haematology Association (2012–2016), Europdonor (till 2015), and advisory work for TRIP, the Dutch Haemovigilance network. She received the Claes Högman Lecture Award of the Swedish Blood Transfusion Society (1997), the Blundell Award of the British Blood Transfusion Society (2009), the Presidential Award of the International Society of Blood Transfusion (2020), and, very recently, the Landsteiner Award (2021). Scientifically, she continued working on non-inherited maternal antigens, an interest she shared with Jon van Rood, and studying factors that influence erythrocyte alloimmunization. Only recently were we informed that Anneke was severely and incurably ill, and her passing away was abrupt. We will remember her words of comfort, wisdom, and inspiration, as we will remember her tremendous scientific drive and encyclopaedic up-to-date knowledge in many fields of medicine. We will never forget the detailed questions she used to have at the end of every lecture she attended, aiming to improve the quality of everyone's contribution to transfusion medicine. She will be deeply missed by her family, friends, and colleagues.

Comparison of the clinical outcomes between NIMA-mismatched and NIPA-mismatched haploidentical hematopoietic stem cell transplantation for patients with hematological malignancies.

The objective of this study was to compare clinical outcomes between noninherited maternal antigen (NIMA)-mismatched and noninherited paternal antigen (NIPA)-mismatched haploidentical hematopoietic stem cell transplantation (haplo-HSCT) among patients with hematological malignancies and perform a subgroup analysis. We retrospectively analyzed 378 patients with hematological malignancies who received haplo-HSCT from NIMA-mismatched (n = 201) and NIPA-mismatched (n = 177) donors between January 2012 and December 2017. The cumulative incidence of 100-d grades II-IV acute graft-versus-host disease (aGVHD) (19.2% vs. 32.8%, P = 0.003) was significantly lower in NIMA mismatch. Multivariate analysis showed that NIMA mismatch was associated with lower incidence of grades II-IV aGVHD and better overall survival (OS) and disease-free survival (DFS). According to the subgroup analysis, the clinical outcomes of older and/or female NIMA mismatches were comparable to those of younger and/or male NIPA mismatches with respect to grades II-IV aGVHD, chronic GVHD (cGVHD), nonrelapse mortality (NRM), relapse, DFS, and OS. In conclusion, this study confirmed the NIMA effect on aGVHD and demonstrated that NIMA mismatch was associated with better survival. In the NIMA mismatch context, donor age and sex did not seem to influence haplo-HSCT, which provides a basis for the selection of sibling donors.

Adoptive Immunotherapy with Cord Blood (CB) Grafts Targeting Shared Inherited Paternal Antigens (IPA) and/or Non-Inherited Maternal Antigens (NIMA) during Induction Treatment for High Risk Myeloid Malignancies: Safety and Preliminary Results

BackgroundSeveral groups have reported use of haploidentical peripheral blood donor cells as adjunct to chemotherapy in remission induction of myeloid leukemia (Colvin et al, BBMT 2009, Gue et al, Blood 2011). Moreover, CB grafts have been associated with greater disease control and enhanced graft-versus-leukemia responses, as a consequence of the fetal-maternal interactions during pregnancy (van Rood et al, PNAS 2009 and PNAS 2012).We evaluated prospectively the feasibility and tolerability of infusing partially HLA matched cord blood units (CBUs) with specific alloreactive properties after salvage chemotherapy to patients (pts) with refractory myeloid leukemia.Patients and MethodsPts with confirmed diagnosis of AML or MDS, according to WHO classification (excluding acute promyelocytic leukemia) who had received two or more previous induction/re-induction regimens were eligible. All pts were treated at NYPH and all CBUs were obtained from the NCBP. The study was performed under FDA IND and was approved by the IRBs of both institutions. Pts received induction chemotherapy followed by CBU infusion (1-3 days later) without any immunosuppression.CBUs eligible for the study contained a pre-cryopreservation Total Nucleated Cell (TNC) dose of 0.5-2.5x107/kg. They were HLA matched at 4-6/6, HLA-A, -B intermediate resolution, -DRB1 high resolution. CBUs had undergone HLA typing of the mother, thus allowing determination of the paternal and maternal antigens. CBUs with shared IPA targets and/or NIMA match were selected for cell therapy.ResultsA total of 34 patients underwent CBU search. Mean CBU number per search was 134 (range: 7-250) with 58% potentially eligible CBUs per pt (range: 5-159). A total of 143 CBUs underwent testing including HLA confirmatory typing. At least one eligible CBU was identified for each pt. Higher HLA allele level match was preferred in the final selection.Of the 34 pts, 23 did not receive treatment because of progressive disease and death (n=8); other clinical trials/treatments (n=6); hematopoietic stem cell transplants (HSCT) (n=9); while one is currently undergoing evaluation. Ten pts have been treated (Table); 8 had AML, 7 with primary induction failure (PIF); one had myeloid blast phase CML and one with high risk MDS. Nine pts had poor risk karyotype and 4 had prior allografts. Median age was 52 years (range: 34-67); median number of prior treatments was 11 (2-15) and median HSCT-CI was 3 (0-7).Of the CBUs infused, six were 5/6 and four were 4/6 HLA matched. The allele level compatibility and presence of shared IPA targets and/or NIMA matches are shown in the Table. CBU median TNC was 90x107 (range: 63-151) and they tended to be “older” with a median cryopreservation time of 10 years. CBUs provided a mean cell dose of 1.66 x 107 TNC/kg (range: 1.1-2.4). Mean post-thaw CD34+ and CD3+ cell doses were 52x103/kg (range: 20-90) and 0.34x107/kg (range: 0.24-0.52; SD: 0.08), respectively, with excellent post-thaw CD34+ viability (93.5%-98.3%).No CBU infusion reactions or cytokine release syndrome were observed. One pt, recipient of a prior allograft with no history of GVHD, experienced skin rash 1 week after CBU infusion. The skin biopsy was consistent with GVHD. No GVHD was observed in the other 9 pts. One pt died of disseminated adenovirus infection early after treatment; viremia was present at the initiation of chemotherapy.Transient CBU chimerism was detected in 5 of the 10 pts as early as one week and as late as 6 months after CBU infusion. Four pts with median pre-treatment BM blast counts of 56% (range 13-94) had objective hematologic responses (Cheson B JCO 2003) with median post-treatment blast counts of 0% (range 0-12), 3 with morphologic leukemia free state and one with a partial response. One patient had aplastic marrow but with flow cytometry evidence of persistent leukemia; while 4 pts recovered with morphologic persistent leukemia. Six pts went on to receive HSCT. Two subsequently relapsed and one died of disseminated adenovirus, while 3 pts remain in remission.ConclusionUse of CBUs as adoptive immunotherapy for pts with refractory myeloid leukemia represents a safe, well tolerated treatment, in which the potential for alloreactivity can be enhanced through the selection of CBUs by targeting shared IPA and NIMA present in the patients. Further, smaller CBUs, unlikely to be adequate grafts for adult transplantation, can be utilized for cell therapy. [Display omitted] DisclosuresRoboz:Cellectis: Research Funding; AbbVie, Agios, Amgen, Amphivena, Array Biopharma Inc., Astex, AstraZeneca, Celator, Celgene, Clovis Oncology, CTI BioPharma, Genoptix, Immune Pharmaceuticals, Janssen Pharmaceuticals, Juno, MedImmune, MEI Pharma, Novartis, Onconova, Pfizer, Roche Pharmace: Consultancy. Ritchie:Celgene: Consultancy, Other: Travel, Speakers Bureau; Pfizer: Consultancy, Other: Research funding to my institution; Incyte: Consultancy, Speakers Bureau; Astellas Pharma: Other: Research funding to my institution; NS Pharma: Other: Research funding to my institution; Bristol-Myers Squibb: Other: Research funding to my institution; Novartis: Consultancy, Other: Research funding to my institution, and travel, Speakers Bureau. Lee:Amgen: Consultancy; Baxalta: Consultancy; Clinipace: Consultancy; Alexion Pharmaceuticals: Consultancy.

Breastfeeding promotes early neonatal regulatory T-cell expansion and immune tolerance of non-inherited maternal antigens.

Breastfeeding is associated with long-term health benefits, such as a lower incidence of childhood infections, asthma, obesity and autoimmune disorders. However, little is known regarding how the maternal and neonatal immune systems interact after parturition when the neonate receives nutrition from maternal breast milk. We undertook a comparative analysis of immune repertoire and function at birth and 3weeks of age in a cohort of 38 term neonates born by caesarean section grouped according to feeding method (breast milk versus formula). We used flow cytometry to study the immune phenotype in neonatal and maternal blood samples and mixed lymphocyte reactions to establish the proliferation response of neonatal versus maternal lymphocytes and vice versa. The microbiome of neonatal stool samples was also investigated using 16S rRNA sequencing. We show that the proportion of regulatory T cells (Tregs) increases in this period and is nearly twofold higher in exclusively breastfed neonates compared with those who received formula milk only. Moreover, breastfed neonates show a specific and Treg-dependent reduction in proliferative T-cell responses to non-inherited maternal antigens (NIMA), associated with a reduction in inflammatory cytokine production. We also observed the enrichment of short chain fatty acid producing taxa (Veillonella and Gemella) in stool samples of exclusively breastfed neonates. These data indicate that exposure of the neonate to maternal cells through breastfeeding acts to drive the maturation of Tregs and 'tolerizes' the neonate towards NIMA.

Controlled induction of immune tolerance by mesenchymal stem cells transferred by maternal microchimerism

Feto-maternal immune tolerance is established during pregnancy; however, its mechanism and maintenance remain underexplored. Here, we investigated whether mesenchymal stem/stromal cells (MSCs) as non-inherited maternal antigens (NIMAs) transferred by maternal microchimerism could induce immune tolerance. We showed that MSCs had a potential equivalent to hematopoietic stem and progenitor cells (HSPCs) to induce immune tolerance and that MSCs were essential to induce tolerance to MSC-specific antigens. Furthermore, we demonstrated that MSCs as NIMAs transferred by maternal microchimerism could induce robust immune tolerance that can be further enhanced using a drug. Our data shed light on induction of immune tolerance and serve as a foundation to develop new therapies using maternally derived cells for autoimmune or genetic diseases.

Adoptive immunotherapy with CB following chemotherapy for patients with refractory myeloid malignancy: chimerism and response

AbstractWe conducted a prospective evaluation of cord blood (CB)–derived adoptive cell therapy, after salvage chemotherapy, for patients with advanced myeloid malignancies and poor prognosis. Previously, we reported safety, feasibility, and preliminary efficacy of this approach. We present updated results in 31 patients who received intensive chemotherapy followed by CB infusion and identify predictors of response. To enhance the antileukemic effect, we selected CB units (CBU) with shared inherited paternal antigens and/or noninherited maternal antigens with the recipients. Twenty-eight patients with acute myeloid leukemia (AML), 2 with myelodysplastic syndrome, and 1 in chronic myeloid leukemia myeloid blast crisis were enrolled; 9 had relapsed after allogeneic transplant. Response was defined as <5% blasts in hypocellular bone marrow at 2 weeks after treatment. Thirteen patients (42%) responded; a rate higher than historical data with chemotherapy only. Twelve had CBU-derived chimerism detected; chimerism was a powerful predictor of response (P < .001). CBU lymphocyte content and a prior transplant were associated with chimerism (P < .01). Safety was acceptable: 3 patients developed mild cytokine release syndrome, 2 had grade 1 and 2 had grade 4 graft-versus-host disease. Seven responders and 6 nonresponders (after additional therapy) received subsequent transplant; 5 are alive (follow-up, 5-47 months). The most common cause of death for nonresponders was disease progression, whereas for responders it was infection. CB-derived adoptive cell therapy is feasible and efficacious for refractory AML. Banked CBU are readily available for treatment. Response depends on chimerism, highlighting the graft-versus-leukemia effect of CB cell therapy. This trial was registered at www.clinicaltrials.gov as #NCT02508324.

Improving cord blood typing with next-generation sequencing: impact of allele-level HLA and NIMA determination on their selection for transplantation.

Allele-level HLA compatibility in cord blood transplantation, together with noninherited maternal antigen or NIMA matching, have been associated with better transplant outcomes. The aim of this work is to develop a cost-efficient high-resolution HLA typing strategy based on next-generation sequencing to improve the quality of the Barcelona Cord Blood Bank's inventory, and to investigate the impact of high-resolution HLA typing and NIMA determination on the preferential selection of cord blood for transplantation. In this line, the developed strategy was validated and the HLA-A, -B, -C, -DRB1, and -DQB1 genes of 5000 cord blood units and 2500 of their associated maternal samples were typed. Subsequently, three study groups of 2012 units each were monitored for up to 2 years: (1) units with high-resolution and maternal HLA typing, (2) units with high-resolution but not maternal typing, and (3) units typed at low-resolution for class I and only high-resolution for HLA-DRB1. Despite a trend toward a greater selection of units with high-resolution typing, no significant impact of these variables was observed. These results highlight the need for evidence-based and globally accepted criteria for cord blood selection, together with the necessity to improve the accessibility of clinicians to donor registry's data.

The effect of maternal grafts in early acute cellular rejection after pediatric living-donor liver transplantation.

Living-donor liver transplantations (LDLTs) with maternal grafts can be more successful than those with paternal grafts because of their tolerance to non-inherited maternal antigens. We reviewed LDLT patients to investigate the relationship between acute rejection and donor sex. LDLT patients between January 2010 and November 2015 were enrolled. ACR was defined by a rejection activity index of > 3. Forty-six patients (22 males and 24 females), of whom 28 had biliary atresia, were enrolled. The median age of the patients was 2.8years and the donor types were maternal (n = 25) and paternal (n = 21). Acute cellular rejection (ACR) was observed in 22 patients. Twelve (48%) of the 25 patients in the maternal group had at least one episode of rejection compared with 10 (48%) of the 21 in the paternal group. Among the patients with ACR, the first rejection in the maternal group occurred significantly earlier than that in the paternal group (p < 0.01). In the multivariable analysis, the only variable significantly related to the first rejection day after LDLT was donor sex (male) (p < 0.005). Our results showed that maternal grafts had an effect on causing earlier ACR in LDLT.

Tolerance to Noninherited Maternal Antigens Allows Successful Second Kidney Transplantation: A Case Report

The 2-way traffic of cells between mother and fetus may introduce noninherited maternal HLA antigens (NIMAs) from the mother to her fetus and expose her to the inherited paternal antigens presented on fetal cells. While contact of maternal immune system with paternal antigens leads to sensitization and development of anti–paternal HLA antibodies, exposure of the fetus to NIMAs can lead to tolerance because of immaturity of the fetal immune system. This state of tolerance is associated with better graft survival from NIMA-mismatched siblings. There are few studies on the effect of tolerance to NIMAs in renal transplant recipients with emphasis on first kidney graft. This reported case combines both effects (sensitization and tolerance) of the same NIMA in a patient who failed the first graft of maternal origin yet demonstrated persistence tolerance toward repeated NIMA mismatches presented on the second sibling donor. To our knowledge, this is the first report of combined effects of the same NIMA encountered by a single patient.

Adoptive Immunotherapy with Cord Blood for the Treatment of Refractory Acute Myelogenous Leukemia: Feasibility, Safety, and Preliminary Outcomes

Adoptive immunotherapy has shown efficacy in patients with relapsed/refractory acute myelogenous leukemia (AML). We conducted a prospective evaluation of cord blood (CB)-based adoptive cell therapy following salvage chemotherapy in patients with AML or myelodysplastic syndrome (MDS) and describe the safety and early outcomes of this approach. To enhance the antileukemic effect, we selected CB units (CBUs) with a shared inherited paternal antigen (IPA) and/or noninherited maternal antigen (NIMA) match with the recipients. Furthermore, the CBUs had total nucleated cell (TNC) dose <2.5 × 107/kg and were at least 4/6 HLA-matched with the patients; a higher allele-level match was preferred. Heavily pretreated adult patients with AML/MDS were enrolled. CBU searches were performed for 50 patients. CBUs with shared IPA targets were identified for all, and CBUs with NIMA matches were found for 80%. Twenty-one patients underwent treatment (AML, primary induction failure, n = 8; refractory relapse, n = 10, including 7 recipients of previous allogeneic HSCT; blast crisis chronic myelogenous leukemia, n = 1; MDS, n = 2). Most received combination chemotherapy; those not fit for intensive treatment received a hypomethylating agent. Response was defined as <10% residual blasts in hypocellular bone marrow at approximately 2 weeks after treatment. Ten of the 19 evaluable patients responded, including 5 of the 7 recipients of previous transplant. Response was seen in 4 of 4 patients with full CBU-derived chimerism, 2 of 2 of those with partial, low-level chimerism and 4 of 12 of the recipients with no detectable CBU chimerism. The most common adverse events were infections (bacterial, n = 5; viral, n = 2; fungal, n = 5). Grade IV acute graft-versus-host disease (GVHD) developed in 2 patients with full CBU chimerism; 2 other patients had grade 1 skin GVHD. A total of 11 patients died, 7 from disease recurrence and 4 from infections (1 early death; the other 3 in remission at the time of death). Overall, 12 patients proceeded to allogeneic HSCT; of those, 7 had responded to treatment, 3 had not (and had received additional therapy), and 2 had persistent minimal residual disease. In conclusion, the use of CB as adoptive immunotherapy in combination with salvage chemotherapy for patients with refractory AML/MDS is feasible, can induce disease control, can serve as a bridge to allogeneic HSCT, and has an acceptable incidence of adverse events. Alloreactivity was enhanced through the selection of CBUs targeting a shared IPA and/or NIMA match with the patients. CBUs with lower cell doses, already available in the CB bank and unlikely to be adequate grafts for adult transplants, can be used for cell therapy within a short time frame.

Role of Regulatory T Cells in Noninherited Maternal Antigen-Related Tolerance in Cord Blood: An in Vitro Study

Cord blood (CB) is an alternative stem cell source for allogeneic hematopoietic stem cell transplantation (HSCT). The unique advantages of using CB as a stem cell source are a degree of permissibility for HLA mismatch, rapid availability, and relatively risk-free cell collection. Because HLA is highly polymorphic and population-specific, optimal HLA-matched unrelated donors or cord blood units (CBUs) might not be available. In view of the possibility that matched CBUs that include noninherited maternal antigens (NIMAs) might contain acceptable HLA mismatches, we attempted to determine the degree of alloreactivity of CB mononuclear cells (MNCs) on stimulation by the maternal, paternal, and unrelated stimulator cells. Suppression of T cell proliferation, cytotoxicity, and a cytokine profile indicating suppressed Th1 and elevated IL-10 and TGF-β1 responses were observed in the mixed lymphocyte reaction in response to NIMAs. The increases in IL-10 and TGF-β1 production may be due to the Th2 response and/or regulatory T cells (Tregs). The reduced IL-10 and TGF-β1 production after CD25 depletion could have been due to removal of Tregs from the CB cells. Thus, Tregs appear to play an important role in the CB MNC response to NIMAs, possibly due to the induction of IL-10 and TGF-β1. We hope that our work can provide some evidence of the beneficial effect of NIMAs.

The effect of NIMA matching in adult unrelated mismatched hematopoietic stem cell transplantation - a joint study of the Acute Leukemia Working Party of the EBMT and the CIBMTR.

Hematological malignancies can be cured by unrelated donor allogeneic HSCT and outcomes are optimized by high-resolution HLA matching at HLA-A, -B, -C, -DRB1 and -DQB1 (10/10 match). If a 10/10 match is unavailable, 9/10 matches may be suitable. Fetal exposure to non-inherited maternal antigens (NIMA) may impart lifelong NIMA tolerance modulating the immune response, as shown in adult haploidentical transplantation. In cord blood transplantation, NIMA matching lowered rates of aGvHD and TRM; in haploidentical transplantation, sibling donors with non-shared maternal antigens showed less grade II-IV aGvHD. This retrospective analysis examined if 9/10 matched unrelated donor HSCT benefits from NIMA matching. DKMS contacted 1,735 donors and obtained 733 (42%) maternal samples. NIMA-matched and -mismatched cases with a minimum follow-up of 1 year were compared by univariate and multivariate analyses adjusted for co-variates for OS, DFS, relapse, TRM and a/cGvHD. The study population (N = 445) comprised 31 NIMA-matched and 414 NIMA-mismatched cases. No significant differences between NIMA-matched and NIMA-mismatched groups were found for any outcomes with similar OS and TRM rates within both groups. This study provides the proof of principle that NIMA matching is possible in the unrelated donor HSCT setting; larger studies may be able to provide significant results.

Non-Inherited Maternal Antigens Identify Acceptable HLA Mismatches: A New Policy for the Hellenic Cord Blood Bank.

Background: During pregnancy, the maternal-fetal contact may lead to the development of tolerance against the maternal human leukocyte antigen (HLA) that is not inherited by the fetus. These non-inherited maternal antigens (NIMAs) define acceptable HLA mismatches; therefore, the number of HLA phenotypes that are suitable matches for patients who need a hematopoietic stem cell transplant could be increased. Cord blood unit (CBU) transplantations to patients mismatched for a HLA loci, but similar to the ΝΙΜAs of the CBU, have a prognosis similar to 6/6-matched ones. Methods: The Hellenic Cord Blood Bank (HCBB) identified the maternal HLA of 380 cord blood donors, specifying the NIMA haplotypes of the related cryostored CBUs. Results: The HCBB extended the pool of HLA phenotypes through the generation of unique virtual phenotypes (VPs). A “VP database” was set up, using Microsoft Office—Access™, in order to provide NIMA-matched CBUs for potential recipients. The effectiveness of VPs’ matching was tested in 80 Greek patients. Conclusion: This methodology may contribute to the increase of the number of available CBUs for patients, in the case where there is no available CBU, or in case an additional one is needed. Through this method, the CBUs could be used faster and more effectively, rather than being cryostored for long periods of time.

Exposure to non-inherited maternal antigens by breastfeeding affects antibody responsiveness.

The observation, by Ray Owen and colleagues in 1954, that D-negative women were less likely to form anti-D antibodies against their D-positive fetus if their mother possessed the D-antigen, was not found in all later studies. We hypothesized that breastfeeding, received by the mother, may affect her immunity against non-inherited maternal red blood cell antigens. We studied a cohort of 125 grandmother-mother-child combinations, from a follow-up study of mothers after intrauterine transfusion of the fetus for alloimmune hemolytic disease. For mismatched red blood cell antigens the mother was exposed to, whether or not antibodies were formed, we determined whether her mother, the grandmother, carried these antigens. The duration for which the mothers were breastfed was estimated by way of a questionnaire. Using multivariate logistic regression analyses, the interaction term (non-inherited maternal antigen exposure by categorized breastfeeding period) showed that a longer breastfeeding period was associated with decreased alloimmunization against non-inherited maternal antigens (adjusted odds ratio 0.66; 95% confidence interval 0.48–0.93). Sensitivity analysis with dichotomized (shorter versus longer) breastfeeding periods showed that this lower risk was reached after two months (aOR 0.22; 95% CI 0.07–0.71) and longer duration of breastfeeding did not seem to provide additional protection. These data suggest that oral neonatal exposure to non-inherited maternal red blood cell antigens through breastfeeding for at least two months diminishes the risk of alloimmunization against these antigens when encountered later in life.

P005 Retrospective study on the effect of non inherited maternal antigen transplantation related mortality in HLA mismatched cord blood transplantation: Hong Kong’s experience

Aim Transplantation-related mortality (TRM) is well-recognized complication of HLA-mismatched cord blood transplantation (CBT). In utero, non-inherited maternal antigen (NIMA) is exposed and recognized by the fetus, which induces T regulator cells to the antigens. It is conceivable that the matching of donor NIMAs in CBTs may alleviate some of the excess mortality associated with this treatment in the recipients. We aim to review if the same concept is observed in the CBTs performed in two paediatric haematopoietic stem cell transplantation centers in Hong Kong. Methods A retrospective analysis was performed and a review of the total of 41 paediatric CBTs performed for haematological malignancies from January 2008 to December 2017 in Hong Kong when the maternal blood samples could be retrieved for HLA typing. Results Only 4 NIMA-matched CBTs for haematological diseases (i.e., the NIMA of the donor cord blood units (CBUs) matched to the patient) were identified and the remaining 37 were non-NIMA-matched CBTs. Due to the small sample size, cases and controls were unable to match on age, disease, disease status, transplantation-conditioning regimen, HLA matching status, and infused cell dose. Two out of 4 (50%) recipients NIMA-matched CBTs died of engraftment failure and disease relapse while 25 out of 37 (68%) non-NIMA-matched died. TRM was similar after NIMA-matched UCBTs compared with NIMA-mismatched CBTs. Overall survival was not higher after NIMA-matched CBT. The 3-year probability of overall survival rates were 50% after NIMA-matched CBTs and 32% after NIMA-mismatched CBTs. Conclusions This retrospective study demonstrated better outcome of NIMA-matched CBTs as compared with NIMA-mismatched CBTs however limited by small sample size and wide variation in the patients’ parameters. When facing the choice of multiple HLA-mismatched CBUs containing adequate cell doses, the advantage of selecting NIMA-matched CBUs on improving survival after mismatched CBT requires further collection of data and experimental evidence.