Effect of particle size on alumina-induced production of reactive oxygen metabolites by human leukocytes.

To assess the role of crystal size in the biologic response, we quantitated the generation of reactive oxygen metabolites in human polymorphonuclear leukocytes (PMNs) or mononuclear leukocytes (MNs) with a chemiluminescence assay using 6 alpha-alumina preparations with average diameters of 0.6, 0.8, 3.2, 7.5, 28 and 68 microns on the basis of equal weights (1 mg/ml), and also on the basis of surface areas (100 cm2/ml). On an equal weight alumina particles induced PMN chemiluminescence in the following order of magnitude: 3.2 microns > 7.5 microns, 0.8 micron > 0.6 micron > 28 microns, 68 microns. The particulates induced MN chemiluminescence: 3.2 microns > 0.8 micron > 0.6 micron > 7.5 microns > 28 microns, 68 microns. On the basis of identical surface areas, alumina elicited PMN chemiluminescence: 3.2 microns > 7.5 microns, 0.8 micron > 0.6 micron, 28 microns, 68 microns. The particulates induced MN chemiluminescence: 3.2 microns > 0.8 micron > 0.6 micron, 7.5 microns > 28 microns, 68 microns. The maximal effect of particle size on the alumina-induced production of reactive oxygen metabolites by human leukocytes was seen at around 3 microns.