Antibodies to Escherichia coli and serum immunoglobulin levels in epileptics on long-term anticonvulsant therapy.

Antibodies to 11 different Escherichia coli (E. coli) serotypes were determined by indirect haemagglutination in 53 epileptics treated with diphenylhydantoin (DPH) and in 53 matched controls. Agglutinins were found more often and at higher titres in epileptics (83 . 4%) than in controls (51 . 7%) (P less than 0 . 05). No correlation between the occurrence of E. coli agglutinins and the serum concentration or clearance of DPH, or abnormal biochemical liver tests could be established. E. coli antibodies were predominantly of the IgM classes, and the percentage of positive reactions was slightly, but not significantly, higher in epileptics with elevated serum IgM (88 . 2%) than in those with normal IgM (83 . 1%) (0 . 20 greater than P greater than 0 . 10). The increased incidence of E. coli agglutinins could not be explained by a low serum IgA concentration which may suggest an impaired secretory immune function. The incidences of positive reactions in epileptics with subnormal (less than 37 mg/100 ml), normal (37-285 mg/100 ml) and elevated (greater than 285 mg/100 ml) serum IgA values were 73 . 7, 84 . 7 and 93 . 7% respectively (0 . 01 greater than P greater than 0 . 001). It is suggested that DPH can both suppress and stimulate the humoral immune response in humans, and that genetic or acquired factors may be of importance for the development of modified immune responses.