The Relationship Between Acetylcholine Receptor Antibody Concentration And The Individualized Progression Of Myasthenia Gravis

Objective Since it was confirmed that acetylcholine receptor autoantibodies(ACh R-Ab)are pathogenic antibodies for myasthenia gravis(MG),there has been no consensus on whether changes in ACh R-Ab concentration can predict or indicate the severity of disease in MG patients.This study aims to investigate the correlation between the ACh R-Ab concentration level and individualized clinical symptoms in ACh R-MG patients.Methods 67 patients who underwent four or more ACh R-Ab concentration tests during 2009-2019 were identified.ELISA was used to detect ACh R-Ab.Cell-based assays(CBA)is used to detect muscle-specific kinase antibody(Mu SK-Ab)and Low-density-lipoprotein-receptor-associated protein 4 antibodies(LRP4-Ab).Myasthenia Gravis Foundation Of America(MGFA)clinical classification,Quantitative Myasthenia Gravis(QMG)score,and MG-specific activities of daily living(MG-ADL)are used to evaluate the clinical condition of patients.Retrospective analysis of relevant data.Spearman correlation analysis was used to describe the correlation between ACh R-Ab concentration and clinical score.While the change of the ACh R-Ab concentration and clinical score is shown in MGFA-antibody concentration-treatment plots.Results(1)399 sera of 67 patients were tested for autoantibodies and their clinical scores were recorded.All serum tests for Mu SK-Ab and LRP4-Ab were negative.All serum tests for Mu SK-Ab and LRP4-Ab were negative.Among them,35 patients underwent thymectomy.In drug treatment,49 patients received immunosuppressive drug therapy,17 patients received a single treatment of pyridostigmine,and 1 patient only received thymectomy without any medication.(2)The analysis of the influencing factors of all MG patients showed that there were no significant correlations between ACh R-Ab levels and the corresponding MGFA,QMG,and MG-ADL scores of patients(rs = 0.29,P < 0.05;rs = 0.17,P < 0.05;rs = 0.23,P < 0.05),while only a slight correlation with age(rs = 0.39,P <0.05).In 16 patients with thymoma,the ACh R-Ab concentration level has a slight correlation with the corresponding MGFA,QMG,and MG-ADL(rs = 0.44,P < 0.05;rs = 0.37,P < 0.05;rs = 0.30,P < 0.05).(3)The results of individual analysis of MG patients showed that 29.4%(5/17)of the pyridostigmine group and 30.6%(15/49)of the immunosuppressive drug group had a positive correlation between the antibody concentration and the clinical classification of MGFA;23.5%(4/17)in the pyridostigmine group,20.4%(10/49)in the immunosuppressive drug group,the MGFA classification change preceded the change in the ACh R-Ab concentration.In patients with oral prednisone dose of 40 mg/d or more,6(46.2%)cases of ACh R-Ab concentration decreased by more than 15%,but there was no uniform pattern of changes in MGFA.For patients with oral non-steroidal immunosuppressive drugs,ACh R-Ab concentration increased with a rate of change greater than 50%,and there is no increase in MGFA.For patients undergoing thymectomy,the concentration of ACh R-Ab decreased in 53.1%(17/32)patients after surgery,and the ACh R-Ab concentration level in 46.9%(15/32)patients did not decrease but increased.However,the clinical MGFA classification decreased in 81.8%(27/32)patients after operation,which was not consistent with the changes in the concentration of ACh R-Ab.Conclusion(1)There is no a consistent correlation between the changes in individual ACh R-Ab concentrations and the severity of clinical symptoms in patients with ACh R-Ab.(2)ACh R-Ab levels is slightly related to age in whole ACh R-MG.(3)Patients receiving oral glucocorticoid doses greater than 40 mg/d may have decreased ACh R-Ab concentrations,while the clinical symptoms did not show significant and consistent improvement.Patients with non-steroidal immunosuppressive drugs may have increased or decreased ACh R-Ab concentrations,while their clinical symptoms often improve to varying degrees.