Pentraxin binding depends on the phase of apoptosis.

Jurkat cells were committed to undergo apoptosis by CD95 cross-linking. The percentage of cells that bound to biotinylated PTX3 (A), to β2-GPI (B), to FITC–annexin V (C), and to PI (D) was assessed by flow cytometry (see “Materials and methods”) at different times after apoptosis induction (panels A-D, x-axis). The ability of cells that bound to PTX3 (green fluorescence, panel E, x-axis), to the PS-binding plasma cofactors β2-GPI (green fluorescence, panel F, x-axis), or to annexin V (green fluorescence, panel G, x-axis) to exclude PI (panels E-G, red fluorescence, y-axis) was assessed by double parametric flow cytometry after 5 hours of treatment with the anti-CD95 monoclonal antibody.