Response of p276-290–reactive T-cell lines to various combinations of DR53-positive APCs and β₂GPI preparations. (A) Various DR53-positive APCs were pulsed with or without native β₂GPI (▪ and □, respectively) and subsequently cocultured with the p276-290–reactive T-cell lines OM7 and KS3. All APCs except allogeneic splenocytes were autologous cells. The antigen-induced T-cell response was measured by [³H]thymidine incorporation. A ▦ indicates a control T-cell line stimulated by a combination of anti-CD3 mAb and phytohemagglutinin (PHA). A representative result from at least 2 independent experiments is shown. (B) Autologous LBLs were pulsed with various β₂GPI preparations and subsequently cocultured with the p276-290–reactive T-cell lines OM7 and KS3. The antigen-induced T-cell response was measured by [³H]thymidine incorporation. The capacity to bind β₂GPI in individual preparations was assessed by inhibition of the interaction between native β₂GPI and immobilized cardiolipin. Results are shown as mean and standard deviation. A representative result from 3 independent experiments is shown.