The neutrophil response to polystyrene microspheres bearing defined surface functional groups

Luminol-induced chemiluminescence (CL) and phagocytosis by human neutrophils was studied using polystyrene microsphere latices as particulate stimuli. Chemiluminescence and phagocytosis parameters were measured for particles bearing carboxyl, hydroxyl, and amino groups, as well as for the underivatized microspheres. The kinetic curves of CL were bimodal, and curve parameters were evaluated for both the early- and late-phase responses. Significant differences were found among the particle surfaces studied. Underivatized particles elicited the greatest response, particles with the amino group stimulated PMN the least, carboxyl- and hydroxyl-group-bearing particles elicited intermediate magnitudes of response. Phagocytosis data were in good agreement with that obtained from CL measurements. These data provide further evidence in favor of the hypothesis that, in protein-free systems, hydrophobic particles are more readily phagocytosed. Additionally they demonstrate that electrostatic interactions are not a significant factor for neutrophil-particle contact.