T cell–derived IFNγ and CD40L/IL-21R signals are crucial for the differentiation of human T-bet ^high CD21 ^low B cells.

The antiphospholipid antibodies present in antiphospholipid syndrome (APS) are directed at a number of phospholipid-binding proteins: β₂ glycoprotein I (β₂GPI), prothrombin, and so on. Antibodies directed at β₂GPI are accepted as a classification criterion for APS, while the presence of antiprothrombin antibodies is not. In the present article, we investigated the possible role of antiphosphatidylserine/prothrombin antibodies (aPS/PT) as marker of APS on a cohort of 295 individuals with APS (95 primary APS and 45 secondary APS) and APS-related diseases. We found aPS/PT to be highly associated with venous thrombosis (immunoglobulin G [IgG] aPS/PT odds ratio [OR], 7.44; 95% confidence interval [CI], 3.97-13.92 and IgM aPS/PT OR, 2.54; 95% CI, 1.35-4.77) and obstetric abnormalities (IgG aPS/PT OR, 2.37; 95% CI, 1.04-5.43), but not with arterial thrombosis. A very high degree of concordance between the concentration of aPS/PT and lupus anticoagulant activity was demonstrated. Therefore, we support the inclusion of aPS/PT determination as second-level assay to confirm APS classification.

Pregnancy and early infancy represent two very particular immunological states. During pregnancy, the haploidentical fetus and the pregnant women develop tolerance mechanisms to avoid rejection; then, just after birth, the neonatal immune system must modulate the transition from the virtually sterile but haploidentical uterus to a world full of antigens and the rapid microbial colonization of the mucosa. B regulatory (Breg) cells are a recently discovered B cell subset thought to play a pivotal role in different conditions such as chronic infections, autoimmunity, cancer, and transplantation among others in addition to pregnancy. This review focuses on the role of Breg cells in pregnancy and early infancy, two special stages of life in which recent studies have positioned Breg cells as important players.

The Toll-like receptor 3 (TLR3) pathway is a key component of the innate immunity that prevents replication of viruses in the CNS. Inborn errors of this pathway (TLR3-pathway deficiency), which includes defects in the genes TLR3, UNC93B1, TRIF, TRAF3, TBK1 and IRF3, occur in 10% of patients with herpes simplex encephalitis (HSE), 1,2 and about 66% of these patients develop relapses of HSE. 1 A recent study showed that 27% of patients with HSE develop autoimmune encephalitis (AE) in the weeks or months ensuing the infection. 3 It is unknown whether TLR3-pathway deficient patients can also develop AE post-HSE. Here we report a patient with TLR3-pathway deficiency who developed HSE and a relapse of the viral infection followed by AE post-HSE, highlighting the fact that TLR3-pathway deficient patients should be carefully followed for both HSE relapses and AE.

Background: Selective IgE deficiency (SIgED) has been previously evaluated in selected patients from allergy units. This study investigates the effects of SIgED on the entire population in a hospital setting and sought to delineate in detail the clinical aspects of SIgED. Methods: A retrospective study of the data obtained from electronic medical records of 52 adult patients (56% female) with a mean age of 43 years and IgE levels of <2.0 kU/L with normal immunoglobulin (Ig) IgG, IgA, and IgM levels, seen at our hospital, without selection bias, from 2010 to 2019. Results: Recurrent upper respiratory infections were recorded in 18 (34.6%) patients, pneumonia was recorded in 16 (30.7%) patients, bronchiectasis was recorded in 16 (30.7%) patients, and asthma was recorded in 10 (19.2%) patients. Eighteen patients (34.6%) suffered autoimmune clinical manifestations either isolated (19%) or combining two or more diseases (15%), Hashimoto’s thyroiditis being the most frequent (19%), which was followed by arthritis (10%) and thrombocytopenia and/or neutropenia (5.7%). Other less frequent associations were Graves’ disease, primary sclerosing cholangitis, Sjögren’s syndrome, and autoimmune hepatitis. Eczematous dermatitis (15.3%), chronic spontaneous urticaria (17.3%), and symptoms of enteropathy (21%) were also highly prevalent. Thirty percent of patients developed malignancies, with non-Hodgkin lymphomas (13.4%) being the most prevalent. Conclusions: The clinical manifestations of SIgED encompass a variety of infectious, non-infectious complications, and malignancy. Since it cannot be ruled out that some type of selection bias occurred in the routine assessment of IgE serum Ievels, prospective studies are required to better characterize SIgED and to determine whether it should be added to the list of antibody deficiencies.