INHIBITION OF ASTROCYTE PROLIFERATION AND BINDING TO BRAIN-TISSUE OF ANTICARDIOLIPIN ANTIBODIES PURIFIED FROM LUPUS SERUM

Polyclonal anticardiolipin antibodies purified from pooled serum samples of patients with systemic lupus erythematosus were shown to have inhibitory effects on cultured normal rat brain astrocytes (RBA-1 cells). Anticardiolipin antibodies at concentrations from 50 to 200-mu-g/ml inhibited the [H-3]thymidine incorporation of RBA-1 cells in a dose dependent manner after three days of culture. A kinetic study showed that anticardiolipin antibodies (100-mu-g/ml) maximally inhibit the proliferation of RBA-1 cells (20.6 (5.1)% of the control value) after incubation for one day. In contrast, human gamma-globulin (100-mu-g/ml) had no effect on these cells. In the presence of anticardiolipin antibodies (100-mu-g/ml), the RBA-1 cells attached to the bottom of wells became spherical and the expression of glial fibrillary acidic protein in the cytoplasm was slightly reduced. Using 3,3'-dihexyloxacarbocyanine iodide as an indicator, anticardiolipin antibodies depolarised the membrane potential of RBA-1 cells after one day of culture. In addition, the percentage binding of RBA-1 cells with anticardiolipin antibodies was greater than with gamma-globulin as determined by flow cytometric analysis. Immunofluorescence staining of brain tissue from BALB/c mice with anticardiolipin antibodies was noted in the corpus callosum, the cellular zone near the corpus callosum, and cells scattered in brain tissue. These results suggest that anticardiolipin antibodies have an inhibitory effect on brain cells and elicit thrombus formation in brain vessels, which plays a part in neuropsychiatric lupus.