Effect of RBCs on nucleosomal DNA fragmentation in neutrophils. Neutrophils were cultured for 24 hours in the presence or absence of 1:1000 RBCs. Cells were harvested and DNA fragmentation was analyzed by agarose gel electrophoresis. Lane 1, molecular weight marker; lane 2, cells cultured without RBCs; lane 3, cells cultured with RBCs; lane 4, cells isolated freshly.