Newborn Screening for Severe T and B Cell Lymphopenia Using TREC/KREC Detection: A Large-Scale Pilot Study of 202,908 Newborns.

Newborn screening (NBS) for severe inborn errors of immunity (IEI), affecting T lymphocytes, and implementing measurements of T cell receptor excision circles (TREC) has been shown to be effective in early diagnosis and improved prognosis of patients with these genetic disorders. Few studies conducted on smaller groups of newborns report results of NBS that also include measurement of kappa-deleting recombination excision circles (KREC) for IEI affecting B lymphocytes. A pilot NBS study utilizing TREC/KREC detection was conducted on 202,908 infants born in 8 regions of Russia over a 14-month period. One hundred thirty-four newborns (0.66‰) were NBS positive after the first test and subsequent retest, 41% of whom were born preterm. After lymphocyte subsets were assessed via flow cytometry, samples of 18 infants (0.09‰) were sent for whole exome sequencing. Confirmed genetic defects were consistent with autosomal recessive agammaglobulinemia in 1/18, severe combined immunodeficiency - in 7/18, 22q11.2DS syndrome - in 4/18, combined immunodeficiency - in 1/18 and trisomy 21 syndrome - in 1/18. Two patients in whom no genetic defect was found met criteria of (severe) combined immunodeficiency with syndromic features. Three patients appeared to have transient lymphopenia. Our findings demonstrate the value of implementing combined TREC/KREC NBS screening and inform the development of policies and guidelines for its integration into routine newborn screening programs.

Overactive WASp in X-linked neutropenia leads to aberrant B-cell division and accelerated plasma cell generation.

BACKGROUND: B-cell affinity maturation in germinal center relies on regulated actin dynamics for cell migration and cell-to-cell communication. Activating mutations in the cytoskeletal regulator Wiskott-Aldrich syndrome protein (WASp) cause X-linked neutropenia (XLN) with reduced serum level of IgA. OBJECTIVE: We investigated the role of B cells in XLN pathogenesis. METHODS: We examined B cells from 6 XLN patients, 2 of whom had novel R268W and S271F mutations in WASp. By using immunized XLN mouse models that carry the corresponding patient mutations, WASp L272P or WASp I296T, we examined the B-cell response. RESULTS: XLN patients had normal naive B cells and plasmablasts, but reduced IgA+ B cells and memory B cells, and poor B-cell proliferation. On immunization, XLN mice had a 2-fold reduction in germinal center B cells in spleen, but with increased generation of plasmablasts and plasma cells. In vitro, XLN B cells showed reduced immunoglobulin class switching and aberrant cell division as well as increased production of immunoglobulin-switched plasma cells. CONCLUSIONS: Overactive WASp predisposes B cells for premature differentiation into plasma cells at the expense of cell proliferation and immunoglobulin class switching.

Cancer-causing MAP2K1 mutation in a mosaic patient with cardio-facio-cutaneous syndrome and immunodeficiency.

RASopathies are disorders caused by germline mutations in genes that encode components of the RAS/mitogen-activated protein kinase (MAPK) pathway. These syndromes share features of developmental delay, facial dysmorphisms, and defects in various organs, as well as cancer predisposition. Somatic mutations of the same pathway are one of the primary causes of cancer. It is thought that germline cancer-causing mutations would be embryonic lethal, as a more severe phenotype was shown in Drosophila and zebrafish embryos with cancer MAP2K1 mutations than in those with RASopathy mutations. Here we report the case of a patient with RASopathy caused by a cancer-associated MAP2K1 p.Phe53Leu mutation. The postzygotic mosaic nature of this mutation could explain the patient's survival.

Procoagulant Activity in Amniotic Fluid Is Associated with Fetal-Derived Extracellular Vesicles.

Procoagulant activity in amniotic fluid (AF) is positively correlated with phosphatidylserine (PS) and tissue factor (TF)-expressing(+) extracellular vesicles (EVs). However, it is unknown if pathological fetal conditions may affect the composition, phenotype, and procoagulant potency of EVs in AF. We sought to evaluate EV-dependent procoagulant activity in AF from pregnant people with fetuses with or without diagnosed chromosomal mutations. AF samples were collected by transabdominal amniocentesis and assessed for common karyotype defects (total n = 11, 7 healthy and 4 abnormal karyotypes). The procoagulant activity of AF was tested using a fibrin generation assay with normal pooled plasma and plasmas deficient in factors XII, XI, IX, X, V, and VII. EV number and phenotype were determined by flow cytometry with anti-CD24 and anti-TF antibodies. We report that factor-VII-, X-, or V-deficient plasmas did not form fibrin clots in the presence of AF. Clotting time was significantly attenuated in AF samples with chromosomal mutations. In addition, CD24+, TF+, and CD24+ TF+ EV counts were significantly lower in this group. Finally, we found a significant correlation between EV counts and the clotting time induced by AF. In conclusion, we show that AF samples with chromosomal mutations had fewer fetal-derived CD24-bearing and TF-bearing EVs, which resulted in diminished procoagulant potency. This suggests that fetal-derived EVs are the predominant source of procoagulant activity in AF.

Efficacy of romiplostim in treatment of thrombocytopenia in children with Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is a life-threatening primary immunodeficiency associated with bleeding of variable severity due to thrombocytopenia. Correction of the thrombocytopenia is of paramount importance for most WAS patients. We report a retrospective analysis of the safety and efficacy of romiplostim treatment in reducing thrombocytopenia and bleeding tendency in 67 children (median age 1·3 years) with genetically confirmed WAS, followed in eight months (range, 1-12 months). Complete or partial primary responses regarding platelet counts were observed in 22 (33%) and 18 (27%) subjects, respectively. Yet, even in the non-responder group, the risk of haemorrhagic events decreased significantly, to 21%, after the first month of treatment. The responses tended to be durable and stable over time, with no significant fluctuations in platelets counts. The results of this retrospective study of a large cohort of WAS patients demonstrates that romiplostim can be used to increase platelet counts and reduce the risks of life-threatening bleeding in WAS patients awaiting haematopoietic stem cell transplantation or forgoing the procedure for various reasons.

Antigen-Specific Stimulation and Expansion of CAR-T Cells Using Membrane Vesicles as Target Cell Surrogates.

Development of CAR-T therapy led to immediate success in the treatment of B cell leukemia. Manufacturing of therapy-competent functional CAR-T cells needs robust protocols for ex vivo/in vitro expansion of modified T-cells. This step is challenging, especially if non-viral low-efficiency delivery protocols are used to generate CAR-T cells. Modern protocols for CAR-T cell expansion are imperfect since non-specific stimulation results in rapid outgrowth of CAR-negative T cells, and removal of feeder cells from mixed cultures necessitates additional purification steps. To develop a specific and improved protocol for CAR-T cell expansion, cell-derived membrane vesicles are taken advantage of, and the simple structural demands of the CAR-antigen interaction. This novel approach is to make antigenic microcytospheres from common cell lines stably expressing surface-bound CAR antigens, and then use them for stimulation and expansion of CAR-T cells. The data presented in this article clearly demonstrate that this protocol produced antigen-specific vesicles with the capacity to induce stronger stimulation, proliferation, and functional activity of CAR-T cells than is possible with existing protocols. It is predicted that this new methodology will significantly advance the ability to obtain improved populations of functional CAR-T cells for therapy.

Plerixafor added to G-CSF allows mobilization of a sufficient number of hematopoietic progenitors without impacting the efficacy of TCR-alpha/beta depletion in pediatric haploidentical and genoidentical donors failing to mobilize with G-CSF alone.

BACKGROUND: Collection of a large number of early hematopoietic progenitors is essential for allogeneic apheresis products intended for TCR-alpha/beta depletion. MATERIALS AND METHODS: We added plerixafor 0.24 mg/kg body weight (bw) on day 4 of high-dose filgrastim mobilization 10 hours prior to apheresis in 16 (30.5%) pediatric allogeneic donors who failed to recover a sufficient number of CD34+ cells. RESULTS: On day 4 of G-CSF, the median CD34+ cell count in peripheral blood was 6 per µL (range 4-9 per µL) in 6 poor mobilizers and 16 per µL (range 12-19 per µL) in insufficient mobilizers. In all donors, the threshold of 50 CD34+ cells/µL was achieved, and the median increase was 14.8-fold in poor mobilizers and 6.5-fold in insufficient mobilizers, whereas it was 3.45-fold increase in those mobilized with G-CSF alone. DISCUSSION: In all donors, a predefined number of >10 × 106 CD34+ cells/kg of recipient bw before depletion was reached in the apheresis product. The use of plerixafor did not affect the purity of further TCR-alpha/beta depletion. Side effects were mild to moderate and consisted of nausea and vomiting. CONCLUSION: Thus, the safety and high efficacy of plerixafor was proven in healthy pediatric allogeneic hematopoietic cell donors.

BCG-Related Inflammatory Syndromes in Severe Combined Immunodeficiency After TCRαß+/CD19+ Depleted HSCT.

INTRODUCTION: The live-attenuated BCG vaccine is known to cause disseminated Mycobacterium bovis infection in patients with severe combined immunodeficiency (SCID). However, BCG-related post-hematopoietic stem cell transplantation (HSCT) immune reconstitution inflammatory syndromes, similar to those described in patients with HIV infections, are less-known complications of SCID. PATIENTS AND METHODS: We reported on 22 BCG-vaccinated SCID patients who had received conditioned allogeneic HSCT with TCRαß+/CD19+ graft depletion. All BCG-vaccinated patients received anti-mycobacterial therapy pre- and post-HSCT. Post-transplant immunosuppression consisted of tacrolimus in 10 patients and of 8 mg/kg tocilizumab (d-1, + 14, + 28) and 10 mg/kg abatacept (d-1, + 5, + 14, + 28) in 11 patients. RESULTS: Twelve patients, five of whom had BCG infection prior to HSCT, developed BCG-related inflammatory syndromes (BCG-IS). Five developed early BCG-IS with the median time of manifestation 11 days after HSCT, corresponding with a dramatic increase of CD3+TCRγδ+ in at least two patients. Early BCG-IS was noted in only one out of 11 patients who received tocilizumab/abatacept and 4 out of 11 patients who did not. Seven patients developed late BCG-IS which corresponded to T cell immune recovery; at the time of manifestation (median 4.2 months after HSCT), the median number of CD3+ cells was 0.42 × 109/ and CD3+CD4+ cells 0.27 × 109/l. In all patients, late BCG-IS was controlled with IL-1 or IL-6 inhibitors. CONCLUSION: BCG-vaccinated SCID patients undergoing allogeneic HSCT with TCRαß+/CD19+ graft depletion are at an increased risk of early and late BCG-IS. Anti-inflammatory therapy with IL-1 and IL-6 blockade is efficient in the prevention of early and treatment of late BCG-IS.

Control of graft-versus-host disease with rabbit anti-thymocyte globulin, rituximab, and bortezomib in TCRαß/CD19-depleted graft transplantation for leukemia in children: a single-center retrospective analysis of two GVHD-prophylaxis regimens.

Both acute GVHD and chronic GVHD remain the leading cause of morbidity and death after allogeneic HSCT. We conducted a retrospective analysis comparing two GVHD-prophylaxis regimens: 35 patients received "Regimen 1" (horse ATG, tacrolimus, and methotrexate) and 46 "Regimen 2" (rabbit ATG, rituximab, and peritransplant bortezomib). All 81 patients with a median age of 9 (0.6-23) years with ALL (n = 31) or AML (n = 50) in complete remission received TCRαß/CD19-depleted transplants between May 2012 and October 2016, from 40 HLA-matched unrelated and 41 haploidentical donors. After a median follow-up of 3.9 years, the CI of acute GVHD II-IV was 15% (95% CI: 7-30) in the "Regimen 2" group and 34% (95% CI: -54) in the "Regimen 1" group, P = .05. "Regimen 2" was also more effective in the prevention of chronic GVHD; the CI at 1 year after HSCT was 7% (95% CI: 2-19) vs 31% (95% CI: 19-51), P = .005. The CI of relapse at 3 years adjusted for the GVHD-prophylaxis regimen groups 31% (95% CI: 19-51) for the "Regimen 1" vs 21% (95% CI: 11-37) for the "Regimen 2", P = .3. The retrospective observation suggests that the use of the rATG, rituximab, and bortezomib was associated with significantly lower rate of GVHD without the loss of anti-leukemic activity.

Combined therapy with IL-1 and JAK inhibitors in a patient with the NLRP1 gene mutation and a complex inflammatory phenotype.

A patient presented with overlapping clinical and laboratory features of 2 rare autoinflammatory diseases, NLRP1-associated autoinflammation with arthritis and dyskeratosis and familial multiple self-healing palmoplantar carcinoma. Her severe inflammatory attack was treated with the IL-1 receptor-α inhibitor anakinra along with the Janus kinase inhibitor ruxolitinib. Three years into the treatment, the patient's inflammatory symptoms are completely in remission.

Allogeneic Hematopoietic Stem Cell Transplantation for Mature T/NK-Cell Lymphomas in Children.

Mature T/NK-cell lymphomas (MTCLs) are a heterogeneous group of lymphoproliferative disorders, relatively rare in adults and children. Allogeneic hematopoietic stem cell transplantation (HSCT) can be considered in some cases as a consolidation and is the first choice for refractory forms and relapses. We retrospectively analyzed 19 pediatric patients with MTCL who received allogeneic hematopoietic stem cell transplantation from a haploidentical or unrelated donor on the αß T cell depletion platform. Among the studied patients, cutaneous T-cell lymphoma was diagnosed in 5, hepatosplenic γδT-cell lymphoma in 4, ALK-positive anaplastic large cell lymphoma in 9 patients, and 1 had nasal T/NK cell lymphoma. All patients received myeloablative conditioning based on treosulfan or total body irradiation. Non-relapse mortality was 5%, the cumulative incidence of relapse or progression at 5 years was 27%, 5-year event-free survival was 67%, and 5-year overall survival was 78%. Thus, our data support that allogeneic αß T-cell-depleted HSCT can provide long-term overall survival of children with high-risk mature T-cell lymphomas.

Post-Transplantation Immunosuppression After TCRΑß/CD19 Graft Depletion Does Not Improve HSCT Outcomes in Primary Immunodeficiency.

We recently demonstrated that TCRαß+/CD19+ graft depletion successfully prevents severe acute and chronic graft-versus-host disease (GVHD) in pediatric patients with primary immunodeficiencies (PID) receiving transplants from both matched unrelated and mismatched related donors. However, in all patients, short-term post-hematopoietic stem cell transplantation (HSCT) immunosuppressive therapy (IST) was used. There are limited data on TCRαß+/CD19+ graft depletion with no post-HSCT IST implementation. In the current study 74 PID patients who underwent first HSCT from matched unrelated (n=51) or mismatched related donors (n=23) with TCRαß+/CD19+ graft depletion were included. All received as a conditioning regimen a combination of treosulfan with fludarabine and either melphalan or thiotepa. In all, thymoglobulin 5 mg/kg (days -5, -4, -3) and rituximab at day -1 were used. In 48 patients, various approaches to short-term post-transplantation IST were used, and 26 patients received no post-HSCT IST. The rates of engraftment, acute and chronic GVHD, survival, and mortality were similar in those who received and did not receive IST, with a slightly higher incidence of graft rejection in patients not receiving IST: 19% in the non-IST group against 13% in the IST group (P = .41). The incidence of cytomegalovirus reactivation was 50% and 39% (P = .50) and Epstein-Barr virus reactivation 10% and 0 (P = .20) in the IST and non-IST groups, respectively. No grade 4 adverse events were seen in both groups, although in 19 of 40 (47.5%) patients receiving calcineurin inhibitors, the therapy was discontinued before day 45. More robust immune recovery with both T- and B-lymphocytes was observed in the non-IST group. To conclude, TCRαß+/CD19+ in combination with particular serotherapy effectively prevents severe acute and chronic GVHD in PID. Regarding remaining risks of infectious complications and additional drug-related toxicity, there are no benefits to post-HSCT IST use in these patients.

BCG Infection in Patients With Inborn Errors of Immunity Receiving the Russian BCG Strain.

BACKGROUND: Bacillus Calmette-Guierin (BCG) vaccination complications are common in inborn errors of immunity (IEI) due to the inability to clear live attenuated Mycobacterium bovis. Various BCG-vaccine strains are used worldwide, and the profile of the Russian BCG strain vaccine complications in IEI is poorly characterized. OBJECTIVE: To evaluate risks of BCG infection in a large cohort of patients with IEI vaccinated with the Russian BCG strain. METHODS: We evaluated 778 patients with IEI vaccinated with the Russian BCG strain. RESULTS: A total of 114 (15%) developed BCG infection, 41 (36%) with local, 19 (17%) with regional, and 54 with (47%) disseminated disease. BCG infection was seen in 58% of the patients with severe combined immunodeficiency (SCID), 82% with chronic granulomatous disease, 50% with innate immune defects, 5% with combined immunodeficiency, and 2% with other IEI. BCG infection presented at a median age of 4 to 5 months in SCID, chronic granulomatous disease, combined immunodeficiency, and other IEI groups versus 12 months in patients with innate immune defects (P < .005). We found no influence of specific genetic defects, CD3+ and natural killer cell numbers in SCID, or dihydrorhodamine test stimulation index values in chronic granulomatous disease on the BCG-infection risks. All patients with SCID received antimycobacterial therapy at SCID diagnosis even in the absence of active BCG infection. More antimycobacterial agents were required in disseminated relative to local or regional infection (P < .0001). Only 1 of 114 patients (with SCID) died of BCG-related complications (<1%). CONCLUSIONS: BCG infection is common in patients with IEI receiving BCG vaccination. Rational early antimycobacterial therapy, combined with anticytokine agents for posttransplant inflammatory syndrome prevention, and treatment in SCID may prevent BCG-related mortality.

The coincidence of two rare diseases with opposite metabolic phenotype: a child with congenital hyperinsulinism and Bloom syndrome.

OBJECTIVES: Congenital hyperinsulinism (CHI) is a group of rare genetic disorders characterized by insulin overproduction. CHI causes life-threatening hypoglycemia in neonates and infants. Bloom syndrome is a rare autosomal recessive disorder caused by mutations in the BLM gene resulting in genetic instability and an elevated rate of spontaneous sister chromatid exchanges. It leads to insulin resistance, early-onset diabetes, dyslipidemia, growth delay, immune deficiency and cancer predisposition. Recent studies demonstrate that the BLM gene is highly expressed in pancreatic islet cells and its mutations can alter the expression of other genes which are associated with apoptosis control and cell proliferation. CASE PRESENTATION: A 5-month-old female patient from consanguineous parents presented with drug-resistant CHI and dysmorphic features. Genetic testing revealed a homozygous mutation in the KCNJ11 gene and an additional homozygous mutation in the BLM gene. While 18F-DOPA PET scan images were consistent with a focal CHI form and intraoperative frozen-section histopathology was consistent with diffuse CHI form, postoperative histopathological examination revealed features of an atypical form. CONCLUSIONS: In our case, the patient carries two distinct diseases with opposite metabolic phenotypes.

Immunogenic epitope panel for accurate detection of non-cross-reactive T cell response to SARS-CoV-2.

The ongoing COVID-19 pandemic calls for more effective diagnostic tools. T cell response assessment serves as an independent indicator of prior COVID-19 exposure while also contributing to a more comprehensive characterization of SARS-CoV-2 immunity. In this study, we systematically assessed the immunogenicity of 118 epitopes with immune cells collected from multiple cohorts of vaccinated, convalescent, healthy unexposed, and SARS-CoV-2-exposed donors. We identified 75 immunogenic epitopes, 24 of which were immunodominant. We further confirmed HLA restriction for 49 epitopes and described association with more than 1 HLA allele for 14 of these. Exclusion of 2 cross-reactive epitopes that generated a response in prepandemic samples left us with a 73-epitope set that offered excellent diagnostic specificity without losing sensitivity compared with full-length antigens, and this evoked a robust cross-reactive response. We subsequently incorporated this set of epitopes into an in vitro diagnostic Corona-T-test, which achieved a diagnostic accuracy of 95% in a clinical trial. In a cohort of asymptomatic seronegative individuals with a history of prolonged SARS-CoV-2 exposure, we observed a complete absence of T cell response to our epitope panel. In combination with strong reactivity to full-length antigens, this suggests that a cross-reactive response might protect these individuals.

Natural Flt3Lg-Based Chimeric Antigen Receptor (Flt3-CAR) T Cells Successfully Target Flt3 on AML Cell Lines.

Relapsed/refractory acute myeloid leukemia (AML) cannot be cured with chemotherapy alone, as the blasts survive the treatment. Chimeric antigen receptor (CAR) approaches for AML are being actively developed. CARs promote immune reactions through recognition of the target molecular epitopes at the surface of cancer cells. The recognition involves the extracellular portion of the CAR protein, which corresponds to either the antibody or the physiological binding partner of the targeted antigen. Here, we design a chimeric receptor with a full-length natural Flt3-ligand recognition module that targets Flt3 tyrosine kinase, known as an adverse marker in AML. We demonstrate specific killing of Flt3-positive THP-1 cells by Flt3-CAR T cells and the lack of cytotoxicity towards Flt3-negative U937 cells. We prove that the inherent cytolytic capacity of T cells is essential for the killing. Finally, we confirm the authenticity of targeting by its competitive dose-dependent inhibition with a soluble Flt3-ligand. The developed system can be viewed as a non-immunogenic functional equivalent of scFv-mediated targeting. The robust in vitro antitumor effects of Flt3-CAR T cells, combined with their low off-target cytotoxicity, hold promise for AML treatment.

Natural products as templates for bioactive compound libraries: synthesis of biaryl derivatives of (+/-)-vasicine.

A reliable and high-yielding procedure for preparation of 7-aryl and 7-heteroaryl derivatives of (+/-)-vasicine in two steps from the naturally occurring material is described. This protocol broadens the chemical space for selective modifications of the vasicine tricyclic structure, thereby making it a valuable starting point for the development of novel compound libraries with potentially beneficial biological profiles.