The significance of anti-endothelial cell antibodies in patients with lupus nephritis and immunoblotting analysis of the target components.

OBJECTIVE

To investigate the prevalence of anti-endothelial cell antibodies and its possible role in the pathogenesis in lupus nephritis.

METHODS

Sera from 58 patients with lupus nephritis were studied. Cellular enzyme linked immunoabsaborbent assay was used to detect anti-endothelial cell antibodies, and immunoblotting technique was performed to determine its specific endothelial target antigens.

RESULTS

36.2% of the patients with lupus nephritis had elevated IgG isotype anti-endothelial cell antibodies. The association was revealed between the presence of anti-endothelial cell antibodies (AECA) and some laboratory and renal biopsy features, such as thrombocytopenia, higher serum IgG level, lower serum C3 level, higher erythrocyte sedimentation rate (ESR), presence of anti-nuclear antibody (ANA), anti-dsDNA antibodies and glomerular thrombosis. Anti-endothelial cell antibodies were consisted of a group of heterogeneous antibodies, and reacted with different endothelial cell antigens which ranged from 12-90 kD in molecular size in immunoblot. A correlation was demonstrated between heavy proteinuria (> 3.5 g/24 hr) and the existence of antibodies against both 27 and 29 kD endothelial cell antigens, an association between the presence of glomerular capillary thrombi and antibody against the 29 kD endothelial cell antigen was also found.

CONCLUSIONS

Lupus nephritis patients with anti-endothelial cell antibodies showed a complex autoimmune disorder and clinical disease activity, and the results also provided an indirect evidence that anti-endothelial cell antibodies might contribute to the pathogenesis of lupus nephritis.