Preparation of Mi-2 antigen and significance of detecting anti-Mi-2 antibody in autoimmune connective tissue diseases / 中华风湿病学杂志

Objective To prepare Mi 2 antigen,detect anti Mi 2 antibody and investigate its significance in autoimmune connective tissue diseases (CTD).Methods Mi 2 antigen was prepared from rabbit thymus acetone powder and purified by DE52 chromatography.Anti Mi 2 antibodies were tested in 40 normal controls and 315 patients with CTD by double immunodiffusion.The distribution of anti Mi 2 antibodies in CTD was analysed.The clinical characteristics of dermatomyositis between anti Mi 2 positive group and negative group were compared.Results The precipitation line developed between the antigen and the standard anti Mi 2 serum.In DE52 chromatography,Mi 2 antigen was found in elute with 0 1 mmol/L and 0 2 mmol/L NaCl.The positive rate of anti Mi 2 antibodies was 26 1%(12/46) in dermatomyositis and 4 5%(2/44) in polymyositis respectively.There were no positive cases in 50 patients with rheumatoid arthritis,30 patients with primary Sjgren syndrome (SS),60 patients with systemic lupus erythematosus,50 patients with systemic sclerosis,35 patients with other CTD and 40 normal controls.The specificity of anti Mi 2 antibody in dermatomyositis was 99 4%.In dermatomyositis,the patients with positive anti Mi 2 antibody usually presented skin lesions at beginning,and most patients had V sign and/or shawl sign during the course of disease.On the other hand,the antibody negative ones manifested muscle involvements initially and easily got fever during the course of disease.There were statistic differences between the two groups in above features ( P