Background Systemic lupus erythematosus (SLE) is an autoimmune disease, where renal involvement is common, being a determinant for bad prognostic. Lupus nephritis is generally associated to the presence of anti-dsDNA. The IgM isotype of this autoantibody, unlike the IgG isotype, seems to be nephroprotector.
Objectives To study the influence of isotypes IgG and IgM anti-dsDNA antibodies on clinical and laboratory manifestations of SLE.
Methods We conducted a cross-sectional study with 137 patients with SLE, in which we explored the presence of isotypes IgG and IgM anti-dsDNA antibodies. The research of anti-dsDNA was performed by indirect immunofluorescence with Crithidia luciliae (CLIF).
Results Fifty-eight (42%) patients had IgG anti-dsDNA reagent and were selected for the study of the IgM isotype. The group of patients who had anti-dsDNA IgG alone (n=43) compared with the group who had concomitant isotypes IgG and IgM (n=15), showed a higher frequency of active urine sediment (34.9% versus 6.7%, p=0.046). Analysis of the median distribution of IgG/IgM anti-dsDNA ratio, according to the presence or absence of clinical and laboratory features, showed a trend of the IgG/IgM ratio be greater in the presence of arthritis and leukopenia/lymphopenia [4 (2-8)versus 1 (1-2), p=0.070 and 4 (3-8) versus 1 (1-4), p=0.066, respectively].
Conclusions Our study showed that the concomitance of the isotypes IgM and IgG anti-dsDNA inhibited the effect of the isotype IgG isolated in association with active urinary sediment. Future studies are needed to clarify the role of anti-dsDNA isotypes in SLE.
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Disclosure of Interest None Declared
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