CD9 and HLA-DR expression by crevicular epithelial cells and polymorphonuclear neutrophils in periodontal disease

Background, aims: The composition of gingival crevicular fluid (GCF) is lik ely to reflect inflammatory modifications that take place in the gingiva du ring periodontal diseases. Method: In this study, GCF was collected at 3 different sites from 23 perio dontal patients. The sites were assessed to be healthy, presenting gingivit is or periodontitis. 10 healthy individuals without any form of periodontal disease formed the control group and were sampled at one site each. The ce ll content of GCF was collected using Durapore Millipore strips, and 2 type s of cells were studied: epithelial cells (EC) and polymorphonuclear neutro phils (PMN). The expression of CD9 and HLA-DR within or on the surface of t hese cells was studied in immunofluorescence on cytospin smears. Results: Both CD9 and HLA-DR expression on EC differed significantly from c ontrol subjects, and the latter decreased according to the severity of the pathology. None of the PMN found in controls expressed CD9 or HLA-DR. Howev er, in periodontal patients, the expression of HLA-DR within PMNs was detec table and increased according to the severity of lesions. CD9 expression on PMNs also increased with inflammation. Conclusion: This study shows that clinically healthy sites of periodontal p atients already present signs of immunological activation characterised by a down modulation of HLA-DR expression on EC and an upregulation of these 2 molecules in PMN.