['To examine the effect of antiphospholipid antibodies on trophoblast expression of adhesion molecules.', 'Primary cytotrophoblast cell cultures.', 'Department of Obstetrics and Gynecology, Catholic University, Rome, Italy.', 'Five normal pregnant women underwent uncomplicated vaginal delivery at 36 weeks of gestation.', 'IgG antibodies were isolated from a patient with antiphospholipid syndrome and from a normal control subject, using protein-G Sepharose columns. Cytotrophoblast cells were dispersed in bicarbonate buffer containing trypsin and DNAse I.', 'We investigated the effects of antiphospholipid antibodies on trophoblast adhesion molecules (alpha1 and alpha5 integrins, E and VE cadherins), both at the protein and mRNA levels.', 'The alpha1 and alpha5 integrins were present in trophoblast cells from 24 hours of culture. Treatment with IgG that were obtained from the patient with antiphospholipid syndrome significantly decreased alpha1 integrin and increased alpha5 integrin at both the mRNA and protein levels. Furthermore, IgG with antiphospholipid antibodies activities induced VE-cadherin down-regulation and the E-cadherin up-regulation at protein and mRNA levels compared with control IgG or untreated cells.'] Do antiphospholid antibodies regulate the expression of trophoblast cell adhesion molecules?