Phagocytosis and Chemiluminescence Response of Granulocytes to Monodisperse Latex Particles of Varying Sizes and Surface Coats

The response of human granulocytes to polystyrene latex beads of diameter 0.1–7 m was measured by luminol-dependent chemiluminescence. In all instances, the response to beads of 3–7 m was definitely higher than with smaller beads. In protein-free medium, the chemiluminescence response was slow compared to that of opsonized zymosan, and the highest response was only 9% of the response to opsonized zymosan. Scanning electron microscopy showed that granulocytes in suspension bound the particles, occasionally by extending rope-like protrusions. When the beads were coated with albumin, the chemiluminescence diminished to about 1/3 of that seen with uncoated beads; however, preincubating the beads in serum led to a large increase with beads of 1.1 m (to 25% of the maximal response to opsonized zymosan) and 3.19 m (to 42%), but with the smallest beads, no increase was noted. "Priming" of the cells with tumor necrosis factor- caused a further increase with serum-coated beads. When uncoated beads of 1.1 m were tested with "primed" cells, there was an increase of 6 times in the chemiluminescence compared to un-"primed" cells.