T15 IgA recognizes apoptotic cells. FACS^® analysis of T15 Ab and control IgA (C-IgA; nonspecific monoclonal) binding to apoptotic PAECs. (a) Apoptosis-induced PAECs were gated into two populations according to PI intensity and FSC as described (7). Region 2 (R2): normal cells and cells in very early apoptosis. Region 1 (R1): cells with dim and bright PI staining (apoptotic). (b) Binding of control IgA and T15 to R2 cells. (c) Binding of control IgA and T15 to R1 cells.