Ethnicity and environmental factors could be involved in the heterogeneity of systemic lupus erythematosus (SLE). We conducted this study to define clinical and serologic correlations and autoantibody clusters in SLE patients in South China. We retrospectively reviewed the records of 917 patients with SLE admitted to our hospital between January 2005 and June 2008.
We found the following associations between autoantibodies and clinical manifestations to be statistically significant: anti-double-stranded DNA (anti-dsDNA) with higher prevalence of renal disorder, leukopenia, and anemia; anti-Sm with higher prevalence of malar rash/discoid rash, pericarditis, and leukopenia; anti-ribonucleoprotein (anti-RNP) with higher prevalence of Raynaud phenomenon and photosensitivity; anti-deoxyribonucleoprotein (anti-DNP) with higher prevalence of arthritis and lower prevalence of renal disorder; anti-Scl-70 with higher prevalence of anemia and Raynaud phenomenon; anti-Jo-1 with higher prevalence of pericarditis; and anti-centromere with higher prevalence of Raynaud phenomenon. Three autoantibody clusters were identified: Cluster 1 (anti-Ro, anti-Sm, and anti-RNP [Ro/Sm/RNP], with a significantly lower percentage of elderly SLE and higher prevalence of photosensitivity, malar rash/discoid rash, Raynaud phenomenon, and leukopenia); Cluster 2 (anti-Ro [Ro], with a lower percentage of pediatric SLE); and Cluster 3 (the absence of anti-extractable nuclear antigen antibodies [ENA ve], with a lower percentage of adult SLE and lower prevalence of alopecia).
In summary, this study not only confirms both anti-dsDNA and anti-Sm as specific markers for classifying SLE, but also demonstrates that photosensitivity is not associated with anti-Ro but with anti-RNP, and a negative association is found between renal disorder and anti-DNP in patients in South China. These results are different from results found in other populations. The higher prevalence of anti-dsDNA and renal disorder results in less difference in the prevalence of anti-dsDNA and renal disorder among the 3 autoantibody clusters in SLE patients in South China, which could be related to ethnicity and widespread industrial pollution in South China.
Abbreviations: ANA = anti-nuclear antibody, anti-DNP = anti-deoxyribonucleoprotein, anti-dsDNA = anti-double-stranded DNA, anti-RNP = anti-ribonucleoprotein, CI = confidence interval, ENA = extractable nuclear antigen antibodies, ENA ve = the absence of anti-extractable nuclear antigen antibodies (Venezuelan cluster), OR= odds ratio, RP = Raynaud phenomenon, SLE = systemic lupus erythematosus.