Normal B cell ranges in infants: A systematic review and meta-analysis

Defining a normal reference range for B cells: A key to diagnosing humoral inborn errors of immunity

B cells are integral components of the adaptive immune response that develop in distinct stages, producing various subsets with specialized roles. Abnormal B cell subsets development is associated with humoral inborn errors of immunity (IEI) and so assessment of B cell subsets is a component of humoral IEI diagnosis and should be compared to a reference range which is age- and population-specific although relatively few studies on B-cell subsets have been published in Africa populations when compared with other populations and not all studies evaluate the same subsets or in the same age-groups. This highlights the need for local studies to establish locally relevant reference ranges.

Sex-specific effects of in utero exposure to per- and polyfluoroalkyl substances on placental development

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants that may impact placental function, and potentially gestational age acceleration (GAA), a deviation from reported and predicted gestational age. GAA potentially represents differences in cell maturation in response to a challenging environment.

OBJECTIVE

This study aimed to characterize the effects of individual and mixtures of PFAS on GAA, cell composition, birth length, and birthweight.

METHODS

Pregnant peoples were recruited from around Little Rock, Arkansas, United States between 2011 and 2014. We utilized placental DNA methylation profiles of 153 healthy pregnancies to calculate GAA and estimate the proportions of six placental cell types. PFAS were quantified in homogenized placental tissue using high-performance liquid chromatography-tandem mass spectrometry. Five PFAS were detected in over 70% of samples. We studied these five PFAS individually using multiple linear regression and as a mixture using quantile g-computation, while adjusting for confounders. The dependent variables in our models included GAA, cell proportions, birthweight, and birth length.

RESULTS

We did not observe associations between PFAS and any of our outcomes in our primary models. While GAA in male placentas were not significantly affected by PFAS, the PFAS mixture associated with decreased syncytiotrophoblast proportion (Ψ = -0.018, 95% CI [-0.032, -0.004]). PFAS mixture did not alter cell proportions in female placentas but was associated with increased GAA (Ψ = 0.269, 95% CI [0.026, 0.513]). Similarly, for females, greater GAA was associated with PFOA (β = 0.141, 95% CI [-0.016,0.040]) and PFOS (β = 0.205, 95% CI [-0.020,0.0416]).

DISCUSSION

We illustrate that PFAS may influence placental development in a sex specific manner. Suggested by decrease in syncytotrophoblast, male placenta may experience a more stunted development due to PFAS exposure. Alternatively, female placentas exhibited increased GAA, a plausible marker of elevated developmental maturation in the face of environmental adversity.

Ofatumumab-exposed breastfeeding in multiple sclerosis patients

BACKGROUND

In Europe, ofatumumab is approved for breastfeeding, but data on its transfer into breast milk and clinical experience are lacking.

OBJECTIVE

To analyze (1) health, development, and adverse events after live vaccination of ofatumumab-exposed breastfed infants and (2) detectability of ofatumumab in breast milk, and to calculate the relative infant dose (RID) using two methods, the traditional method and a second method considering maternal exposure to multiple ofatumumab doses and extended collection period.

METHODS

In this observational study, clinical data were collected by standardized telephone interviews up to 2 years postpartum. Breastmilk samples were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Twelve mothers started ofatumumab-exposed breastfeeding between 0.6 and 19.6 months postpartum. Infants showed neither abnormalities in infections, antibiotic use, or hospitalizations nor developmental delay. Five infants with available B cells had normal levels. Eight (66.7%) infants received live vaccines during/after exposed breastfeeding. None had complications. Ofatumumab concentration in breast milk varied widely between a median RID of average concentration 0.027% (range: 0.019%-0.115%) using method 1 and 2.912% (range: 1.301%-12.322%) using method 2.

CONCLUSION

Ofatumumab-exposed breastfeeding did not adversely affect infants' health or development. Despite higher RIDs using the more appropriate method 2, the risk of substantial antibody absorption by infants appears to be low.

Pregnancy and Infant Outcomes in Women With Multiple Sclerosis Treated With Ocrelizumab

BACKGROUND AND OBJECTIVES

Ocrelizumab labeling advises contraception for women during treatment and for 6-12 months thereafter. Because pregnancies may occur during this time, it is critical to understand pregnancy and infant outcomes in women with multiple sclerosis (MS) after ocrelizumab exposure.

METHODS

Pregnancy cases reported to Roche global pharmacovigilance until 12 July 2023 were analyzed. In utero exposure was defined if the last ocrelizumab infusion occurred in the 3 months before the last menstrual period or during pregnancy. Breastfeeding exposure was defined if at least one infusion occurred while breastfeeding. Fetal death was termed spontaneous abortion (SA) if < 22 complete gestational weeks (GWs) and stillbirth if later. Live births (LBs) were preterm if < 37 complete GWs. Major congenital anomalies (MCAs), infant outcomes, and maternal complications were also analyzed.

RESULTS

In total, 3,244 pregnancies were reported in women with MS receiving ocrelizumab. The median maternal age was 32 years (Q1-Q3: 29-35 years), and most women had relapsing MS (65.6%). Of 2,444 prospectively reported pregnancies, 855 were exposed to ocrelizumab in utero (512 with a known outcome), 574 were nonexposed, and the remaining 1,015 had unknown timing of exposure. Most (83.6%; 956/1,144) of the pregnancies with a known outcome resulted in LBs (exposed, 84.2%; nonexposed, 88.3%). The exposed and nonexposed groups had similar proportions of other important pregnancy outcomes (preterm births, 9.5% vs 8.7%; SA, 7.4% vs 9.1%). Elective abortions were more frequent in the exposed group (7.4%, vs 1.7% in the nonexposed group). The proportion of LBs with MCAs was similar between the exposed and nonexposed groups (2.1% vs 1.9%) and within epidemiologic background rates. In the exposed group, one stillbirth and one neonatal death were prospectively reported.

DISCUSSION

In this analysis of a large pregnancy outcome dataset for an anti-CD20 in MS, in utero exposure to ocrelizumab was not associated with an increased risk of adverse pregnancy or infant outcomes. These data will enable neurologists and women with MS to make more informed decisions around family planning, balancing safety risks to the fetus/infant against the importance of disease control in the mother.

Neonatal Outcomes following 2 Cases of Maternal CAR-T Therapy for High-Grade B-Cell Lymphoma

INTRODUCTION

Chimeric antigen receptor T cells (CAR-Ts) targeting CD19 represent a significant advance in treatment for patients with relapsed/refractory B-cell malignancies. Although a significant minority of recipients are women during their reproductive years, there is a paucity of data regarding pregnancy and neonatal outcomes in women previously treated with CAR-T. This is important as maternal T cells are known to cross the placenta and into breastmilk during pregnancy and breastfeeding, respectively.

CASE PRESENTATION

Here we present two successful pregnancies following CAR-T therapy where both neonates were initially breastfed. These represent the first cases of neonates born following CAR-T therapy comprehensively described in medical literature.

CONCLUSION

Pregnancy following CAR-T therapy does not appear to be associated with adverse neonatal outcomes. Further work is required to delineate the outcomes in this population.

Emerging insights into atypical B cells in pediatric chronic infectious diseases and immune system disorders: T(o)-bet on control of B-cell immune activation

Repetitive or persistent cellular stimulation in vivo has been associated with the development of a heterogeneous B-cell population that exhibits a distinctive phenotype and, in addition to classical B-cell markers, often expresses the transcription factor T-bet and myeloid marker CD11c. Research suggests that this atypical population consists of B cells with distinct B-cell receptor specificities capable of binding the antigens responsible for their development. The expansion of this population occurs in the presence of chronic inflammatory conditions and autoimmune diseases where different nomenclatures have been used to describe them. However, as a result of the diverse contexts in which they have been investigated, these cells have remained largely enigmatic, with much ambiguity remaining regarding their phenotype and function in humoral immune response as well as their role in autoimmunity. Atypical B cells have garnered considerable interest because of their ability to produce specific antibodies and/or autoantibodies and because of their association with key disease manifestations. Although they have been widely described in the context of adults, little information is present for children. Therefore, the aim of this narrative review is to describe the characteristics of this population, suggest their function in pediatric immune-related diseases and chronic infections, and explore their potential therapeutic avenues.

Anti-CD20 monoclonal antibody therapy in postpartum women with neurological conditions

OBJECTIVE

Postpartum, patients with multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) have increased risk for disease activity. Anti-CD20 IgG1 monoclonal antibodies (mAb) are increasingly used as disease-modifying therapies (DMTs). Patients may wish to both breastfeed and resume DMT postpartum. This study aimed to determine the transfer of anti-CD20 IgG1 mAbs, ocrelizumab, and rituximab (OCR/RTX), into mature breastmilk and describe maternal and infant outcomes.

METHODS

Fifty-seven cis-women receiving OCR/RTX after 59 pregnancies and their infants were enrolled and followed up to 12M postpartum or 90 days post-infusion. Breastmilk was collected pre-infusion and serially up to 90 days and assayed for mAb concentration. Medical records and patients' questionnaire responses were obtained to assess neurologic, breastfeeding, and infant development outcomes.

RESULTS

The median average concentration of mAb in breastmilk was low (OCR: 0.08 μg/mL, range 0.05-0.4; RTX: 0.03 μg/mL, range 0.005-0.3). Concentration peaked 1-7 days post-infusion in most (77%) and was nearly undetectable after 90 days. Median average relative infant dose was <1% (OCR: 0.1%, range 0.07-0.7; RTX: 0.04%, range 0.005-0.3). Forty-three participants continued to breastfeed post-infusion. At 8-12 months, the proportion of infants' growth between the 3rd and 97th World Health Organization percentiles did not differ for breastfed (36/40) and non-breastfed (14/16, p > 0.05) infants; neither did the proportion with normal development (breastfed: 37/41, non-breastfed: 11/13; p > 0.05). After postpartum infusion, two mothers experienced a clinical relapse.

INTERPRETATION

These confirm minimal transfer of mAb into breastmilk. Anti-CD20 mAb therapy stabilizes MS activity before conception to the postpartum period, and postpartum treatments appears to be safe and well-tolerated for both mother and infant.

Automated EuroFlow approach for standardized in-depth dissection of human circulating B-cells and plasma cells

Background

Multiparameter flow cytometry (FC) immunophenotyping is a key tool for detailed identification and characterization of human blood leucocytes, including B-lymphocytes and plasma cells (PC). However, currently used conventional data analysis strategies require extensive expertise, are time consuming, and show limited reproducibility.

Objective

Here, we designed, constructed and validated an automated database-guided gating and identification (AGI) approach for fast and standardized in-depth dissection of B-lymphocyte and PC populations in human blood.

Methods

For this purpose, 213 FC standard (FCS) datafiles corresponding to umbilical cord and peripheral blood samples from healthy and patient volunteers, stained with the 14-color 18-antibody EuroFlow BIgH-IMM panel, were used.

Results

The BIgH-IMM antibody panel allowed identification of 117 different B-lymphocyte and PC subsets. Samples from 36 healthy donors were stained and 14 of the datafiles that fulfilled strict inclusion criteria were analysed by an expert flow cytometrist to build the EuroFlow BIgH-IMM database. Data contained in the datafiles was then merged into a reference database that was uploaded in the Infinicyt software (Cytognos, Salamanca, Spain). Subsequently, we compared the results of manual gating (MG) with the performance of two classification algorithms -hierarchical algorithm vs two-step algorithm- for AGI of the cell populations present in 5 randomly selected FCS datafiles. The hierarchical AGI algorithm showed higher correlation values vs conventional MG (r2 of 0.94 vs. 0.88 for the two-step AGI algorithm) and was further validated in a set of 177 FCS datafiles against conventional expert-based MG. For virtually all identifiable cell populations a highly significant correlation was observed between the two approaches (r2>0.81 for 79% of all B-cell populations identified), with a significantly lower median time of analysis per sample (6 vs. 40 min, p=0.001) for the AGI tool vs. MG, respectively and both intra-sample (median CV of 1.7% vs. 10.4% by MG, p<0.001) and inter-expert (median CV of 3.9% vs. 17.3% by MG by 2 experts, p<0.001) variability.

Conclusion

Our results show that compared to conventional FC data analysis strategies, the here proposed AGI tool is a faster, more robust, reproducible, and standardized approach for in-depth analysis of B-lymphocyte and PC subsets circulating in human blood.