[The evidence of antibodies against motor endplates of the skeletal muscle in myasthenia gravis with the double immune-fluorescence technique (author's transl)].

Studies were undertaken on sera of 66 patients for detecting antibodies to motor endplates using a double immunofluorescence method according to Sondag-Tschroots et al. Rat tongue was used as antigenic substrate. Strong positive results at a serum dilution of 1: 20 were found only in patients with myasthenia gravis (15 out of 42 patients approximately equal to 35.7%). Titres between 1: 20 and 1: 1,280 occurred. 3 of 8 patients with chronic active hepatitis and with circulating antibodies to smooth muscle and 2 of 4 patients with autoimmune disorders and weakly positive antibodies in their 1: 20 diluted serum. The used rat tongue as antigenic substrate seems to be more suitable than diaphragm for detecting of such and other antibodies.