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Dendritic cell (DC) vaccines are promising for immunotherapy, and their production using CD34 + hematopoietic stem cells (HPSCs) from patients with chronic myelogenous leukemia (CML) and healthy donors is well established. However, the generation of CD1a + CD14 - DCs and their functional properties in patients with CML remain elusive. Here, we aimed to study the biology of DCs generated from CD34 -/low HPSCs and evaluate the status of their BCR/ABL translocation, ability to stimulate T cells, and capacity of endocytosis compared to DCs derived from CD34 + HPSCs from both patients with CML and healthy donors. CD1a + CD14 - DCs were generated from CD34 -/low HPSCs and evaluated morphologically and functionally. CD34 + cells are frequently selected for transplantation and the entire CD34 -/low HPSC fraction is wasted. Here, we anticipated the CD34 - HPSC subset to constitute an invaluable source for acquiring DCs for immunotherapy. CD34 + and CD34 - HPSCs were sorted from the bone marrow samples of CML patients and healthy donors and differentiated ex vivo in a similar way. DCs from CD34 - Lin - and CD34 + Lin - HPSCs expressed comparable surface markers (CD80, CD83, CD86, HLA-DR, CD40, and CD54). Functional analysis revealed that DCs acquired from both subsets retained a potent allogeneic T cell stimulatory capacity and an efficient phagocytic ability and showed a similar BCR/ABL translocation status. In conclusion, DCs were successfully differentiated from the CD34 - Lin - cell subset and showed potent functional capacities, indicating their potential for application in immunotherapy and basic research., Competing Interests: None., (AJTR Copyright © 2023.)

Arthrogryposis multiplex congenita (AMC) is an important birth defect with a significant genetic contribution. Many syndromic forms of AMC have been described, but remain unsolved at the molecular level. In this report, we describe a novel syndromic form of AMC in two multiplex consanguineous families from Saudi Arabia and Oman. The phenotype is highly consistent, and comprises neurogenic arthrogryposis, microcephaly, brain malformation (absent corpus callosum), optic atrophy, limb fractures, profound global developmental delay, and early lethality. Whole-exome sequencing revealed a different homozygous truncating variant in SCYL2 in each of the two families. SCYL2 is a component of clathrin-coated vesicles, and deficiency of its mouse ortholog results in a severe neurological phenotype that largely recapitulates the phenotype observed in our patients. Our results suggest that severe neurogenic arthrogryposis with brain malformation is the human phenotypic consequence of SCYL2 loss of function mutations.

NK cell activity is tuned by a balance of activating and inhibitory signals transmitted via their respective receptors, including killer immunoglobulin-like receptors (KIRs). The impact of NK cells on graft-versus-leukemia following hematopoietic stem cell transplantation (HSCT) is well established. These effects sometimes lead to GvHD. The link between KIR/HLA interaction and GvHD remains unclear. Herein, we studied the impact of the KIR/HLA interaction on HSCT outcomes in a longitudinal follow-up study of a highly consanguineous HLA-matched related cohort. Peripheral blood DNA was collected from HSCT donor-recipient pairs (n = 87), including 41 AML pairs. KIR and HLA were genotyped and significant results were only measured when matching KIR (donor) with HLA (recipients). GvHD was observed in 47% of patients. KIR2DL1_C2 and 2DS2_C1 (P = 0.02 and 0.04, respectively) matching was associated with an increased incidence of acute GvHD in AML donor-recipient pairs. The rate of chronic GvHD also rose in AML patients who were matched for KIR2DS1_C2 (P = 0.004) and had either KIR2DL2 or KIR2DS2 (P = 0.03). In conclusion, matching of KIR2DL1, 2DS1, and 2DS2 in donors with their HLA-C ligands in recipients is associated with increased GvHD, and holds potential for selection of HSCT donors.

Background: Truncus arteriosus (TA) is characterised by failure of septation of the outflow tract into aortic and pulmonary trunks and is associated with high morbidity and mortality. Although ranked among the least common congenital heart defects, TA provides an excellent model for the role of individual genes in cardiac morphogenesis as exemplified by TBX1 deficiency caused by point mutations or, more commonly, hemizygosity as part of the 22q11.2 deletion syndrome. The latter genetic lesion, however, is only observed in a proportion of patients with TA, which suggests the presence of additional disease genes., Objective: To identify novel genes that cause Mendelian forms of TA., Methods and Results: We exploited the occurrence of monogenic forms of TA in the Saudi population, which is characterised by high consanguinity, a feature conducive to the occurrence of Mendelian phenocopies of complex phenotypes as we and others have shown. Indeed, we demonstrate in two multiplex consanguineous families that we are able to map TA to regions of autozygosity in which whole-exome sequencing revealed homozygous truncating mutations in PRKD1 (encoding a kinase derepressor of MAF2) and NRP1 (encoding a coreceptor of vascular endothelial growth factor (VEGFA)). Previous work has demonstrated that Prkd1(-/-) is embryonic lethal and that its tissue-specific deletion results in abnormal heart remodelling, whereas Nrp1(-/-) develops TA. Surprisingly, molecular karyotyping to exclude 22q11.2 deletion syndrome in the replication cohort of 17 simplex TA cases revealed a de novo hemizygous deletion that encompasses PRDM1, deficiency of which also results in TA phenotype in mouse., Conclusions: Our results expand the repertoire of molecular lesions in chromatin remodelling and transcription factors that are implicated in the pathogenesis of congenital heart disease in humans and attest to the power of monogenic forms of congenital heart diseases as a complementary approach to dissect the genetics of these complex phenotypes., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)