IgG2 deficiency and intractable epilepsy of childhood.

Twelve children with intractable childhood epilepsy (ICE) were treated with high-dose intravenous immunoglobulins every 21 days for 6 months after immunologic and neurologic evaluations had been carried out. 50% (6/12) were found to have a deficiency of serum IgG2 and all but 1 of these responded to treatment with marked reduction in the daily number of seizures assessed both clinically and electroencephalographically. The response to treatment was, in fact, significantly higher in the children with IgG2 deficiency than in the others. IgG4 deficiency, observed in 5 children, did not affect treatment response. It is suggested that IgG2 deficiency may predispose to some form of viral encephalitis which may trigger an immune mechanism leading to the ICE.