β₂GPI/PS-induced T-cell response in PBMC cultures with or without IgG derived from APS plasma. (A) PBMCs obtained from APS3 were cultured in triplicate with β₂GPI/PS in medium supplemented with untreated or IgG-depleted autologous APS plasma, or healthy plasma. Purified IgG (1 μg/mL-1 mg/mL) or IgG F(ab′)₂ (100 μg/mL) from APS3 was added to the cultures. After 7 days, the T-cell proliferative response induced by β₂GPI/PS was measured by ³H-thymidine incorporation. Results are shown as mean (column) and standard deviation (error bar). Concordant results were obtained with a sample from APS4. (B) PBMCs derived from APS3 were cultured in triplicate with or without β₂GPI/PS in medium supplemented with autologous APS plasma or healthy plasma. An anti-β₂GPI antibody–depleted or mock-treated autologous IgG fraction was added to the initiation of cultures. After 7 days, the T-cell proliferative response was measured by ³H-thymidine incorporation. Results are shown as mean (column) and standard deviation (error bar). Concordant results were obtained with a sample from APS4.