PMA treatment of neutrophils results in rapid morphologic changes accompanied by externalization of PS. (A) Cytospin preparation of neutrophils cultured in medium alone (1) or treated for 3 hours with 200 nmol/L PMA (2). Note the presence of numerous vacuoles in the cytoplasm and the coalescence of the nuclear lobes after PMA treatment. Original magnification × 100. (B) PS exposure in unstimulated (panel 1) and PMA-treated (panel 2, 200 nmol/L) neutrophils after 3 hours of culture. PS exposure was determined by flow cytometric analysis of annexin V binding as described in Materials and Methods. The percentage PS exposure is indicated. PMA treatment also caused a marked increase in forward scatter of these cells, indicative of an increase in cell size (data not shown). Similar results were obtained with three independent donors.