The role of antiphospholipid antibodies in lupus nephropathy

Although several clinical and morphological changes observed in overt systemic lupus erythematosus have been associated with the presence of antiphospholipid antibodies (aPL), the relation between these antibodies and lupus nephropathy (LN) is not clear. Twenty-three patients with biopsyproved LN were retrospectively studied (average age 28.5 +/- 12.3 years, all women) in order to investigate the relationship between the presence of aPL and clinical and immunobiological data. The average follow-up period was 55 +/- 42 months. The presence of aPL (IgG and IgM) was detected at least once in all patients by ELISA and/or lupus anticoagulant (kaolin time). Seven patients (30.4%) were aPL+, and the remainder aPL-. We did not find differences related to age, period of follow-up, blood pressure and livedo reticularis. However the prevalence of thrombosis, strokes and hemolysis was slightly higher in the aPL+ patients. The levels of antinuclear antibodies or anti-DNA antibodies, immunoglobulins and complement serum levels (C3, C4) were also similar in both groups. In the aPL+ group, proteinuria was significantly higher than in aPL- cases (2.21 +/- 1.5 and 0.91 +/- 1.07 g/24 h, respectively; p = 0.029). The renal histological pattern in both series was similar. However, microthrombosis in the glomerular capillary lumens was more frequent in the aPL+ group. The evolution of renal function was less favorable in aPL+ patients when compared with aPL- patients. We conclude that the presence of aPL in patients with LN is associated with several characteristics of renal impairment which may contribute to its evolution.