A genetic disease associated with enhanced susceptibility to infection, autoimmunity, and decreased antibody production is common variable immune deficiency (CVID). Mutations in the tumor necrosis factor receptor superfamily member TACI, are associated with CVID and autoimmunity development. Interestingly, autoimmunity develops in CVID patients with only one mutated copy of TACI, and CVID patients with two mutated TACI alleles do not develop autoimmunity.
In this issue of the Journal of Clinical Investigation, Eric Meffre and colleagues at Yale University evaluated B cell activation and tolerance development in healthy individuals and CVID patients with one or two mutated copies of TACI. The authors found that CVID patients with a single altered TACI allele maintained some residual B cell responsiveness that promoted development of autoantibodies, whereas individuals with 2 mutated copies of TACI have complete impairment of B cell responses, which likely prevents autoimmunity.
In the companion commentary, Antonia La Cava of the University of California Los Angeles suggests that targeting residual B cell activity in CVID patients that are heterozygous for TACI mutations may provide clinical relief.