Drug-induced IgA deficiency in epileptic patients.

Serum concentrations of IgA, IgG, and IgM were determined by immunodiffusion technique in 184 epileptic patients and 95 healthy individuals. Twenty-one percent of adult and 42% of children patients receiving anticonvulsants had serum IgA levels below 0.6 mg/ml (the lowest value detected in normal sera). Serum concentrations in non-drug-taking epileptic patients were normal. Deviations in IgG/IgM concentrations were smaller and less consistent. Serum IgA level was determined at intervals before and during phenytoin treatments. A fall in the IgA level occurred in several patients. In two patients, IgA deficiency developed within two to three months of treatment. Low IgA-responders were more frequent among men and children. The IgA anomaly was not specific for any type of epilepsy.