Polyclonal anticardiolipin antibodies purified from sera of patients with active systemic lupus erythematosus induce apoptosis of the cultured glomerular mesangial cells

Objective: To test the effect of anticardiolipin antibodies (aCL) on cultured glomerular mesangial cells with regard to their expression of apoptosis-related genes. Methods: aCL purified from active lupus sera by cardiolipin micelles were incubated with cultured rodent mesangial cells (RMC). Morphological changes of the RMC were observed. The genomic DNA was extracted for the detection of apoptosis. The total cell RNA was extracted for detection of Fas, c-myc, p53, and bcl-2 transcripts by reverse transcription-polymerase chain reaction. Results: aCL (100 GPL-U/0.1 mg protein/ml) bound to RMC more prominent than human IgG (100 μg/ml). The antibodies suppressed RMC proliferation in a dose-dependent manner. The RMC were undergoing apoptosis as evidenced by morphologic changes, fluorescein-annexin V staining and appearance of nucleosome-sized DNA fragments. RMC spontaneously express p53 and c-myc but not Fas or bcl-2. aCL (100 GPL-U/ml) enhanced the expression of Fas but not other apoptosis-related genes and suppressed the intracellular tyrosine phosphorylation. Conclusions: Binding of aCL can induce apoptosis of the RMC. The aCL may be implicated in the pathogenesis of lupus nephritis.