Arf1-dependent LRBA recruitment to Rab4 endosomes is required for endolysosome homeostasis.

Deleterious mutations in the lipopolysaccharide responsive beige-like anchor protein (LRBA) gene cause severe childhood immune dysregulation. The complexity of the symptoms involving multiple organs and the broad range of unpredictable clinical manifestations of LRBA deficiency complicate the choice of therapeutic interventions. Although LRBA has been linked to Rab11-dependent trafficking of the immune checkpoint protein CTLA-4, its precise cellular role remains elusive.

Regulatory B cells in patients suffering from inborn errors of immunity with severe immune dysregulation.

Background: Immune dysregulation as a result of an inborn error of immunity (IEI) leads to the complicated symptoms of refractory multi-organ immune dysregulation. B lymphocytes with immune regulatory capacity (Breg) are activated by environmental triggers and act as regulators of the immune response as observed in several autoimmune diseases.

Objective: We sought to investigate the Breg profile and the CD21 expressing B cells of patients with LRBA deficiency (N = 6) and non-LRBA deficiency IEI (N = 13) with overlapping clinical symptoms of immune dysregulation.