The Detection Of Different Antibodies Of Myasthenia Gravis And Its Clinical Significances

Objective: To test whether myasthenia gravis(MG) patients have acetylcholine receptor(ACh R), muscle-specific receptor tyrosine kinase(Mu SK) and low-density lipoprotein receptor-related protein 4(LRP4) antibodies in serum and their pathogenesis and clinical characteristics are essential. Methods: This study developed 116 sera with MG, 40 patients with other neurological diseases(OND), and 40 healthy control(HC) subjects from Department of Neurology in Affiliated Hospital of Guiyang Medical University and Second Affiliated Hospital of Guiyang College of Traditional Chinese Medicine. For the detection of ACh R and Mu SK antibodies, ELISA was used; and for LRP4 antibody, a cell based assay(CBA) method was used. Results:(1) There were 116 patients in the study(F: M=1.47:1). The frequency of ACh R-Ab was 50.0%. Among the 56 patients of MG without ACh R antibodies, only 6 had Mu SK antibodies(10.7%), and 2 had both ACh R-Ab and Mu SK-Ab(double-seropositive MG, d SP-MG). The frequency of ACh R-Ab and Mu SK-Ab was lower than most Caucasian studies, but was similar to exsisting Chinese researches.(2)50 MG patients(43.1%) lacked ACh R-Ab and Mu SK-Ab were referred to as double-seronegative MG(d SN-MG).(3)It was showed that a proportion of d SN-MG patients have autoantibodies to LRP4 using the CBA. LRP4-Ab was detected in 2 of 50 patients(4%) with d SN-MG. No LRP4 antibodies were identified in sera from other MG subtypes, 40 healthy controls and 40 other neurologic diseases control subjects.(4)These subtypes of MG had some different clinical features: Thymic abnormalities such as hyperplasia and thymoma were frequently related to ACh R-MG. Mu SK-MG patients had more prominent bulbar involvement than other MG populations, and they were unlikely to be improved with acetylcholinesterase inhibitors(ACh EI). In contrast with ACh R-Ab, Mu SK-Ab titers lever was associated with its severity. Also, the clinical characteristics of the 2 LRP4-MG patients were studied. Both of them had same ethnic background and presented thymic changes and isolated ocular symptoms(Osserman I). They got full remission after treated with ACh EI and small dose prednisone. Conclusion: LRP4-Ab was detected in the sera of 4% of patients with d SN-MG in Guizhou, China. These findings may contribute to the timely diagnosis of MG and indicate that LRP4 is probably a new target for autoantibodies that are pathogenic through different immunopathogenic processes.