IgE deficient patients have no IgE-encoding B cells in the periphery – a pilot study

Abstract

While we learn more about different clinical presentations of IgE-deficient patients (IgE<2.5 kU/L), the mechanism resulting in IgE-deficiency is unknown. Through this small pilot study, we sought to investigate the frequency of IgE-encoding B cells in the peripheral blood of IgE-deficient individuals. Peripheral blood mononuclear cells (PBMCs) were collected from 5 IgE-deficient and 5 non-IgE deficient patients with different allergy-like symptoms. Cells were counted and assessed for viability before culturing in the presence of murine anti-human kappa/lambda, irradiated murine fibroblasts expressing human CD40-ligand, B-cell activating factor and IL-21. The cells were screened for IgE secretion after 6 days of incubation. All IgE-deficient patients had undetectable IgE levels (<2 kU/L). The median IgE level in non-IgE deficient patients was 1615 kU/L (range: 260-4340 kU/L). IgE-deficient patients had allergic rhinoconjunctivitis-like symptoms, two patients had associated asthma, and one drug allergy. The non-IgE deficient patients had asthma, food allergies and atopic dermatitis. The median PBMCs cultured was similar between IgE-deficient (16 cells x106, range: 8-16 cells x106) and non-IgE deficient individuals (24 cells x106, range: 8-24 cells x106, p=0.2). However, while the median frequency of IgE-encoding B cells was 2.9 cells/107 PBMCs (range: 2.5-4.8 cells/107 PBMCs) in non-IgE deficient patients, the IgE-deficient patients had zero IgE-encoding B cells. The abscence of IgE-encoding B cells in the serum of IgE-deficient patients suggests a defect in either these cells' survival, or in the IgE-class switching process. Further research is needed to elucidate the exact mechanism resulting in absence of serum IgE in certain individuals.