| Objectives:1. To establish a quantitative detection system by ELISA for anti-Sm D1 antibody and indirect ELISA for anti-CAF-1 antibody in order to explore their diagnostic sensitivity and specificity in patients with systemic lupus erythematosus(SLE), as well as to evaluate disease devolopment and curative effect.2. To evaluate the correlation between anti-Sm D1 antibody or anti-CAF-1 antibody and the conventional SLE markers, in order to establish a combined detection model on SLE with desired sensitivity and specificity.Methods:1. 164 subjects were divided into three groups: 60 cases with SLE; 54 cases with other connective tissue diseases(18 cases with rheumatoid arthritis, 11 cases with Sjogren’s syndrome, 10 cases with systemic sclerosis, 8 caseswith dermatomyositis, 7 cases with mixed connective tissue diseases as non-SLE; 50 cases as healthy control.2. The anti-Sm D1 antibody was detected by quantitative ELISA, anti-CAF-1 was detected by indirect ELISA and anti-ds DNA antibody was detected by indirect immunofluorescent assay, anti-SM antibody, Anua and ARPA was detected by linear immunoblotting assay respectively. Meanwhile, the laboratory examination(including routine blood test, routine urine test, Ig G, Ig A, Ig M, C3, C4) were recorded and the clinical performance of SLE patients(such as fever, rash, joint pain(≥2), central nervous system involvement and so on) was also included.3. Statistical analysis: For normal distribution measurement data which was presented as mean ± standard deviation, one way ANOVA test was used for within-groupcomparisons, and LSD test was used for between-group comparisons. For non-normally distributed measurement data which was showed with median, the comparison between-group was realized with Mann Whitney U test. χ2 test was used for the comparison of counting data. Kappa analysis was applied for correlation analysis. P<0.05 was considered to indicate statistical significance. Statistical analysis was performed using SPSS for Windows, version 13.0.Results:1. The level of anti-Sm D1 antibody in SLE group was 31.55(13.98-128.84) U/ml,which was significantly higher than that of non-SLE group(13.48)(12.50-19.80) U/ml and normal control group(13.62)(12.50-17.93) U/ml(P<0.01).2. The OD value(450nm) of anti-CAF-1 antibody of SLE group was much higher than that both of non-SLE group(0.27 ± 0.17 vs. 0.21 ±0.09, P<0.05) and the normal control group(0.27 ± 0.17 vs. 0.20±0.06, P<0.01).3. The positive rate of anti-Sm D1 antibody in SLE group was up to 53.3%(32 / 60),which was the highest among the six auto-antibodies and significantly higher than non-SLE group( 14.8%) and the normal control group(2.0%)(P < 0.01). The positive rate of anti-CAF-1 antibody was 26.7% and significantly higher than the non-SLE group(19.2%)and the normal control group(4.0%)(P < 0.01).4. The level of anti-Sm D1 antibody showed highly correlation with C3, C4 and Ig G,which SLE patients with positive anti-Sm D1 antibody were accompanied by obviously lower C3, C4 level but higher Ig G level in serum than SLE patients with negative anti-Sm D1 antibody. There was no correlation between the anti-Sm D1 antibody level and the other clinical data(including gender, age, albuminuria, rash, arthritis, fever, central nervous system involvement, erythrocyte sedimentation rate, white blood cell, hemoglobin,Ig A, Ig M in SLE patients)(P>0.05). Meanwhile, there was no correlation between the anti-CAF-1 antibody level and the clinical data mentioned above(P>0.05).5. In SLE group,the positive rate of Anti-Sm D1 was 53.3% that was obviously higher than the conventional SLE serological markers( the positive rate of anti-ds DNA antibodywas33.3%, the positive rate of Sm, Anu A and ARPA was 13.3%,25.0% and 25.0%). The anti-Sm D1 antibody was coincident with anti-ds DNA antibody, anti-Sm antibody rather than Anu A, ARPA.6. In SLE group, there was no significant difference between positive rate of anti-CAF-1 antibody and conventional serological markers of SLE(anti-ds DNA antibody,anti-Sm antibody, Anu A, ARPA) which showed that there was no consistency between them.(P>0.05).7. The positive rate of anti-Sm D1 antibody in SLE group was significantly higher than that of anti-CAF-1 antibody(P<0.01), however, there was no consistency between them(P > 0.05).8. Detection of anti-Sm D1 antibody alone showed the highest sensitivity(53.3%),negative predictive value(77.2%) and accuracy(77.4%) with highest specificity(100.0%)and positive predictive(100.0%) in patients with SLE compared with detection of anti-CAF antibody and conventional serological markers. Combined detection of anti-Sm D1 antibody and conventional serological markers increased sensitivity from53.3%(32/60) to 71.7%(43/60) and improved the accuracy from 77.4%(127/164)to 82.9%(136/164); Combined detection of anti-CAF antibody and conventional serological markers increased sensitivity from 26.7%(16/60) to 70.0%(42/60) and improved the accuracy from68.9%(113/164) to 84.1%(138/164); And detection all of them increased sensitivity from55.0%(33/60) to 81.7%(49/60) and improved the accuracy from 81.7%(134/164) to 86.0%(141/164).Conclusions:1. Anti-Sm D1 antibody could be served as a specific marker for SLE diagnosis.2. Anti-Sm D1 antibody showed highly correlation with C3, C4 and Ig G which was contributed to evaluation of SLE developing.3. Anti-CAF-1 antibody could also be applied for SLE diagnosis without correlation with SLE condiction.4. Combination of detecting anti-Sm D1 antibody, and /or anti-CAF-1 antibody and conventional serological indicators(anti-ds DNA antibody, anti-Sm antibody, Anu A, ARPA)of SLE could improve the diagnostic sensitivity of SLE. |
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