[The application of reagents of a biotin-avidin system in detecting anti-acetylcholine receptor antibody].

Using ABC-ELISA developed for the determination of anti-AchR antibody, 113 blood samples from patients with MG, 100 from blood donors and 78 from patients with other autoimmune and muscle- related diseases were tested. The results showed that the positive rate of MG reached 87% (99 of 113), while none of the samples from blood donors and only 1 from SLE patients gave positive result. The neutralization test indicated that the assay was specific and the cow AchR could be used as a new antigen for antibody detection in human MG. Besides, the method was shown to be reproducible. Therefore, we consider that ABC-ELISA is a useful assay method for the study of MG. The possible reasons of the presence of anti-AchR negative phenomenon in MG are also discussed.