An in vitro study of neutrophils obtained from the normal gingival sulcus

Neutrophils (PMN) are considered to be key components in the protection of the periodontium against pathogenic bacteria. We therefore compared five of the major characteristics of peripheral blood PMN (PB‐PMN) (adherence, chemotaxis, phagocytosis, oxidaiive metabolism, and lysosomal granules) to those of normal crevicular neutrophils (CR‐PMN) isolated from the same individuals. The data indicate that the presence of Fc and C3b receptors, and the production of superoxide are similar in CR‐PMN and PB‐PMN. In addition, healthy gingival sulci harbor a high percentage of stimulated PMN as determined by the nitroblue tetrazolium (NBT) reduction assay. The percentage of CR‐PMN which phagocytized opsonized red blood cells (RBC) was lower than that of PB‐PMN. The in vitro migration of CR‐PMN was reduced as compared to that of PB‐PMN. Crevicular neutrophils also have a diminished ability to adhere to glass surfaces which may be related to a direct non‐cytotoxic effect of gingival fluid component(s) on CR‐PMN. In addition, morphologic evidence indicates that specific granules are more depleted than azurophil granules in CR‐PMN. Interpretation of studies of neutrophil functions in periodontal diseases must consider the observed differences between normal peripheral blood and crevicular neutrophils.