CD11c ⁺ atypical B cells (ABCs) are an alternative memory B cell lineage associated with immunization, infection, and autoimmunity. However, the factors that drive the transcriptional program of ABCs have not been identified, and the function of this population remains incompletely understood. Here, we identified candidate transcription factors associated with the ABC population based on a human tonsillar B cell single-cell dataset. We identified CD11c ⁺ B cells in mice with a similar transcriptomic signature to human ABCs, and using an optimized CRISPR-Cas9 knockdown screen, we observed that loss of zinc finger E-box binding homeobox 2 (Zeb2) impaired ABC formation. Furthermore, ZEB2 haplo-insufficient Mowat-Wilson syndrome (MWS) patients have decreased circulating ABCs in the blood. In Cd23 ^Cre/+ Zeb2 ^fl/fl mice with impaired ABC formation, ABCs were dispensable for efficient humoral responses after Plasmodium sporozoite immunization but were required to control recrudescent blood-stage malaria. Immune phenotyping revealed that ABCs drive optimal T follicular helper (T _FH ) cell formation and germinal center (GC) responses and they reside at the red/white pulp border, likely permitting better access to pathogen antigens for presentation. Collectively, our study shows that ABC formation is dependent on Zeb2, and these cells can limit recrudescent infection by sustaining GC reactions.

Biallelic inactivating mutations in DOCK8 cause a combined immunodeficiency characterized by severe pathogen infections, eczema, allergies, malignancy, and impaired humoral responses. These clinical features result from functional defects in most lymphocyte lineages. Thus, DOCK8 plays a key role in immune cell function. Hematopoietic stem cell transplant (HSCT) is curative for DOCK8 deficiency. While previous reports have described clinical outcomes for DOCK8 deficiency following HSCT, the effect on lymphocyte reconstitution and function has not been investigated. Our study determined whether defects in lymphocyte differentiation and function in DOCK8-deficient patients were restored following HSCT. DOCK8-deficient T and B lymphocytes exhibited aberrant activation and effector function in vivo and in vitro. Frequencies of αβ T and MAIT cells were reduced, while γδT cells were increased in DOCK8-deficient patients. HSCT improved abnormal lymphocyte function in DOCK8-deficient patients. Elevated total and allergen-specific IgE in DOCK8-deficient patients decreased over time following HSCT. Our results document the extensive catalog of cellular defects in DOCK8-deficient patients and the efficacy of HSCT in correcting these defects, concurrent with improvements in clinical phenotypes. Overall, our findings reveal mechanisms at a functional cellular level for improvements in clinical features of DOCK8 deficiency after HSCT, identify biomarkers that correlate with improved clinical outcomes, and inform the general dynamics of immune reconstitution in patients with monogenic immune disorders following HSCT.

Intramuscular adrenaline remains the first-line drug in updated anaphylaxis guidelines.

The Zeb2 gene encodes a transcription factor (ZEB2) that acts as an important immune mediator in mice, where it is expressed in early-activated effector CD8 T cells, and limits effector differentiation. Zeb2 homozygous knockout mice have deficits in CD8 T cells and NK cells. Mowat–Wilson syndrome (MWS) is a rare genetic disease resulting from heterozygous mutations in ZEB2 causing disease by haploinsufficiency. Whether ZEB2 exhibits similar expression patterns in human CD8 T cells is unknown, and MWS patients have not been comprehensively studied to identify changes in CD8 lymphocytes and NK cells, or manifestations of immunodeficiency. By using transcriptomic assessment, we demonstrated that ZEB2 is expressed in early-activated effector CD8 T cells of healthy human volunteers following vaccinia inoculation and found evidence of a role for TGFß-1/SMAD signaling in these cells. A broad immunological assessment of six genetically diagnosed MWS patients identified two patients with a history of recurrent sinopulmonary infections, one of whom had recurrent oral candidiasis, one with lymphopenia, two with thrombocytopenia and three with detectable anti-nuclear antibodies. Immunoglobulin levels, including functional antibody responses to protein and polysaccharide vaccination, were normal. The MWS patients had a significantly lower CD8 T cell subset as % of lymphocytes, compared to healthy controls (median 16.4% vs. 25%, p = 0.0048), and resulting increased CD4:CD8 ratio (2.6 vs. 1.8; p = 0.038). CD8 T cells responded normally to mitogen stimulation in vitro and memory CD8 T cells exhibited normal proportions of subsets with important tissue-specific homing markers and cytotoxic effector molecules. There was a trend towards a decrease in the CD8 T effector memory subset (3.3% vs. 5.9%; p = 0.19). NK cell subsets were normal. This is the first evidence that ZEB2 is expressed in early-activated human effector CD8 T cells, and that haploinsufficiency of ZEB2 in MWS patients had a slight effect on immune function, skewing T cells away from CD8 differentiation. To date there is insufficient evidence to support an immunodeficiency occurring in MWS patients.

Aim: Penicillin allergy labels are frequently encountered in children and are associated with significant harms. Most children are falsely labelled and can safely tolerate a penicillin but delabelling strategies are underutilised and paediatric‐specific resources are lacking. The aim of this study was to evaluate an allergy assessment tool for children in hospital.Methods: We evaluated a paediatric‐adapted penicillin allergy assessment tool, using an online survey of clinicians in a tertiary paediatric hospital, with 10 hypothetical potential penicillin allergy or adverse reaction cases (including non‐allergy reactions). For each case, respondents were asked to use the tool to assign a reaction phenotype and recommend management. We determined the tool's sensitivity, specificity and acceptability to end users.Results: We evaluated 30 complete survey responses from senior and junior medical staff, nurses and pharmacists. The tool's overall sensitivity was 80.7% (95% confidence interval (CI) 74.2–87.1%) for assigning the correct reaction phenotype and 85.3% (95% CI 79.4–91.3%) for appropriate management. The tool had high sensitivity for identifying immediate hypersensitivity reactions at 95.6% (95% CI 90.2–100%). Most respondents agreed or strongly agreed that they would use the tool in their practice (22/30, 73.3%).Conclusion: This survey evaluated a paediatric‐adapted penicillin allergy assessment tool in a tertiary paediatric hospital among multidisciplinary clinician groups. The tool performed well overall and had high safety in identifying immediate hypersensitivity reactions. Further research to support implementation of allergy assessment and delabelling programmes among children is required.