Immune tolerance induction in patients with IgA anaphylactoid reactions following long‐term intravenous IgG treatment

Summary To date, there is very little information regarding the pathomechanism of IgA anaphylactoid reactions and the management of affected patients. Five adult patients with common variable immunodeficiency (CVID) and a history of anaphylactic reactions due to the administration of immunoglobulin preparations were studied. The activity of anti‐IgA was determined by the gel agglutination technique using IgA‐coated beads. Antibodies to IgA were detected in the serum of all five patients. Initially, IgA ‘depleted’ intravenous (i.v.) IgG preparations were infused carefully into the patients until the activity of anti‐IgA was decreased significantly or became undetectable. Subsequently, unselected i.v. IgG preparations were infused, and the activity of anti‐IgA was abolished in all cases. Intravenous IgG long‐term administration results in tolerance induction in patients with IgA anaphylactoid reactions. This tolerance appears to be related to antibody blockage in the circulation and an inhibition of antibody production. Most importantly, IgA appears to play an important role in the treatment of CVID. Patients with IgA anaphylactoid reactions can be treated safely with IgA containing i.v. IgG preparations following tolerance induction.