Anticardiolipin antibodies in patients with primary antiphospholipid syndrome: A correlation between IgG titre and antibody-induced cell dysfunctions in neuronal cell cultures

Anticardiolipin antibodies (aCL) of the immunoglobulin (Ig) G isotype have been significantly associated with neurological manifestations of antiphospholipid syndrome (APS). In a previous study we described the direct pathogenic effects of IgG aCL on living neurons in culture. Therefore, we studied the IgG aCL titre as a factor influencing the extent of this effect. Seventeen patients with a history of primary antiphospholipid syndrome were grouped according to their IgG aCL titre into low positive (GPL less than or equal to 40), high positive (40 < GPL < 100) and very high positive (GPL > 100). IgG from these patients were incubated with cerebellar neurons in primary culture for 24h and the effect was evaluated by using the tetrazolium salt (MTT) assay. We found that almost all patients' IgGs reduced cell viability in vitro, but the differences in the extent of the effect were statistically significant only for patients with > 40 GPL. Our results reinforce the causal association between increasing level of IgG aCL and clinical features of aPS.