Expression of CD14, CD16 and CD45RA on monocytes from periodontitis patients

Background and objective: Peripheral blood monocytes are a heterogeneous population, with phenotypes that change on activation or differentiation. Most of the monocytes express lipopolysaccharide (LPS) receptor, CD14 intensely, and do not express Fc gamma receptor III, CD16 (CD14(++)CD16(-) monocytes). But monocytes expressing CD16 with reduced CD14 (CD14(+)CD16(+) monocytes) increase in inflammatory diseases as well as sepsis and bacteremia in hemodialysis patients. CD45RA is expressed on activated monocytes, and is regarded as an activation marker of peripheral blood monocytes. The purpose of this study was to determine the phenotypic and functional alteration of monocytes in periodontitis patients. Methods: Peripheral blood was collected from 33 aggressive periodontitis patients (22 females, 11 males), 55 chronic periodontitis patients (35 females, 20 males) and 30 healthy subjects (16 females, 14 males), and the expression of CD14, CD16 and CD45RA on monocytes was determined using flow cytometry. The production of interleukin-6 (IL-6) by CD16(+) and CD16(-) monocytes stimulated with LPS from Escherichia coli and Actinobacillus actinomycetemcomitans was also examined using flow cytometry. Results: The percentage of CD14(+)CD16(+) monocytes was significantly increased in chronic periodontitis patients. Percentage of monocytes expressing CD45RA was significantly increased in aggressive periodontitis patients compared to healthy subjects. CD16(+) and CD16(-) monocytes produced IL-6 in response to LPS from E. coli and A. actinomycetemcomitans, and the percentage of IL-6 producing cells was higher in CD16(+) monocytes than CD16(-) monocytes, suggesting that CD14(+)CD16(+) monocytes represent a hyper-reactive phenotype. Conclusions: The present study demonstrated that CD14(+)CD16(+) monocytes and CD45RA(+) monocytes were increased in chronic and aggressive periodontitis, respectively. These findings suggest that alteration of monocytes in periodontitis patients could be evaluated by monitoring the surface expression of CD14, CD16 and CD45RA on monocytes.