Carbamazepine: effect on IgG subclasses in epileptic patients.

IgG subclass concentrations were determined in sera from 20 epileptic patients before carbamazepine therapy and after 6 weeks of treatment. Subclass-specific monoclonal antibodies were used in an ELISA technique. Carbamazepine reduced the IgG2 concentration in 13 patients, and the mean value fell from 3.21 to 2.47 g/L during the carbamazepine treatment (p less than 0.01). This IgG2 decrease was maintained after 4 and 12 months of carbamazepine therapy. IgG1, IgG3, and IgG4 concentrations did not change. IgG2 deficiency was not seen. The reduction in IgG2 was not related to the carbamazepine serum concentration within the therapeutic range, to the type of epilepsy, or to the age of the patient. The carbamazepine-induced reduction of IgG2 in serum may indicate an altered immune response to certain antigens, preferentially to carbohydrates.