Clinical Significance Of Precise Tests For Detection Of Autoantibodies

Objective:Autoantibodies detection has important clinical significance in the diagnosis of autoimmune diseases (AID), judgement of disease severity and the treatment effect of AID. With the progress of immune detection technology including the found of new antibody specificity target antigen and the appearing of more autoantibodies detection technology, there are new problems of how to evaluate the method and diagnostic value of autoantibodies detection. By determination the patients’ autoantibodies on systemic lupus erythematosus (SLE), Non-systemic lupus erythematosus (Non-SLE) and Non-autoimmune disease (Non-AID), We mainly compared the precise autoantibody determination method with the conventional one and then assessed the advantages of the two methods and at the same time judged its diagnostic value with other related immune indices.Methods:The study was conducted in135patients from department of Rheumatology and department of Nephrology, and20healthy volunteers in the first affiliated hospital of DaLian medical university. The controlled healthy ones were normal in physical examination and no significant lesions in major organs, without diabetes and other chronic disease. The experimental ones were the patients of autoimmune disease for the first time in the hospital or recurrence before using hormone and other drugs. The135patients were divided into three groups according to be AID (SLE and Non-SLE) or not:group Ⅰ,33patients of SLE; group Ⅱ,59Non-SLE patients including21of Rheumatoid arthritis (RA),15of Mixed connective tissue disease (MCTD),13of Sjogren’s syndrome (SS),5Systemic sclerosis (SSc), and5of Polymyositis and dermatomyositis (PM/DM); group Ⅲ,43of Non-AID patients including12of Coronary heart disease,15of Kidney disease,8of malignant tumor, and8of pneumonia. The group IV was the control one including20healthy examinees. The autoantibodies in each group were detected by the method of enzyme immunoassay-antinuclear antibody screen (EIA-AN A). The indexes of the autoantibodies include dsDNA, histones, ribosomal P protein, nRNP, Sm, SSA, SSB, Scl-70, Jo-1and the centromere. At the same time, by indirect fluorescence immunoassay (IIF-ANA), the antinuclear antibodies (ANA) in each group were also determinated, using the substrate of Hep2cells and mouse livers. In addition, the ASO and RF, and other immune indices such as IgG, IgA, IgM, complement C3and C4were also measured in each group. All of the above indices higher than the lowest detection line were diluted. The dilution ratio of EIA-ANA was1:200,1:2000,1:20000,1:200000,1:2000000; the ratio of IIF-ANA was100,1:320,1:1000,1:3200,1:10000; and the ratio of the other immune indices was1:2,1:4,1:8,1:16,1:32. Finally, precise determinations of the results were calculated by the formula and the conventional ones were the clinical laboratory results. All data were statistically analyzed by SPSS11.5software. Variance analysis was used in comparison among groups, and Spear correlation analysis was tested in the correlation of two methods.Results:①The test results in precise EIA-ANA and conventional EIA-ANA did not entirely accord with each other, because there are15patients(group I,4;group II,5;group,6) whose results were negative in conventional EIA-ANA while positive in precise EIA-ANA, which showed the sensitivity of precise EIA-ANA be better.②The specificity of precise EIA-ANA may be better than conventional IIF-ANA, because the low titer ANA in group III were not detected by the former method contrasted to be detected by the latter one, although the high titer ANA were both detected by the two methods. The results of the two methods used in155patients showed that the Spearman correlation coefficient r was0.673and the average coincidence rate was72.9%, which illustrated a good correlation with each other. The coincidence rate was over84%between39patients in SLE group and20ones in control group, was the lower of71%in Non-SLE group, and was the lowest of58%in Non-AID group.③Both the precise RF and conventional RF were efficient in Non-SLE group and inefficient in SLE group, and the average coincidence rate between them was98.71%. In addition, the coincidence rate of precise ASO and conventional ASO reached100%.④The results of other immune indices determination showed that there were very significant difference of complement C3and C4among the groups (P<0.01). Complement C3and complement C4of SLE group were obviously reduced in comparison with control groups, and there were no significant difference of IgG, IgA, IgM among groups(P>0.05).Conclusion:The precise tests for detection of autoantibodies may help us to improve the detection effects of antinuclear antibodies in practice.