Fc(alpha) receptor I (CD89) on neutrophils in periodontal lesions

In this study, we have examined the occurrence of FcalphaRI-bearing cells in gingival tissue, gingival fluid and blood, in search for possible roles of IgA and FcalphaRI in periodontal lesions.

Gingival biopsies from inflamed and healthy sites were obtained from patients with chronic marginal periodontitis. Sections of inflamed gingiva were examined by immunofluorescence techniques and compared to sections from healthy sites. Smears were made from blood and gingival crevicular fluid and similarly studied.

Dense infiltrates of neutrophils with strong expression of FcalphaRI (and FcgammaRIII) were found in connective tissue and epithelium of the apical part of periodontal pockets from diseased sites. In contrast, only few such cells were found in healthy gingiva from the same patients. Neutrophils in gingival fluid, tissue and blood expressed FcalphaRI with similar intensity, whereas the expression of FcgammaRIII was significantly decreased in gingival crevicular fluid. Considerable numbers of bacteria from gingival plaque were found to be covered by IgA.

It is suggested that FcalphaRI on neutrophils may play an important rôle in elimination of IgA-opsonized bacteria, both in periodontal tissue and the adjacent pockets.