Phenotypical and functional analysis of T cells in periodontitis

To explore aspects of cellular immune responses in the pathogenesis of periodontitis we analyzed phenotype and function of peripheral T cells. Two groups of subjects participated: one group consisted of 10 highly susceptible patients with severe periodontitis (mean age 29 years) and a control group consisted of 10 age, gender and race matched subjects with gingivitis. From all subjects peripheral blood was collected. The results showed that the numbers of CD3+, CD4+ and CD8+ T cells as well as the CD4/CD8 ratio, and the proliferative capacity of T cells, were not different between the two groups of subjects. Also, proportions of naive and memory T cells for both the CD4+ and CD8+ subpopulations were not different. Functional heterogeneity within the CD4+ and CD8+ T cell compartments was determined by intracellular analysis of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production. On the basis of these latter analyses among CD4+ and CD8+ cells, T helper (Th) 1 or Th2 function and T cytotoxic (Tc) 1 or Tc2 function, respectively, could be deduced. No significant differences in proportions of CD4+ and CD8+ T cells positive for intracellular IFN-gamma or IL-4 were observed between periodontitis patients and gingivitis controls; however a higher level of intracellular IL-4 in CD8+ T cells was seen in periodontitis patients. This might indicate that there is a shift towards a Tc2 function within the CD8+ T cell subpopulation. The current explorative study suggests that further research into the role of CD8+ T cells in the pathogenesis of periodontitis is warranted.