Immunoregulatory control of Th1/Th2 cytokine profiles in periodontal disease

Over the past decade, numerous studies have attempted to delineate the Thl/Th2 cytokine profile in chronic periodontitis in humans. While some controversy still exists regarding these profiles, the fact that the stable periodontal lesion is identical to a delayed type hypersensitivity reaction while the progressive lesion involves large numbers of B cells and plasma cells, strongly suggests that the stable lesion is mediated by Th1 cells and the progressive lesion by Th2 cells. The control of Th1 and/or Th2 expression is therefore fundamental in understanding the immunoregulatory mechanisms in chronic periodontitis. In this context, high affinity T cell receptor (TCR) interactions seem to direct a Th1 response while low affinity TCR involvement tends towards a Th2 response. As yet however, TCR affinity in chronic periodontitis has not been investigated. Other mechanisms which may control Thl/Th2 profiles include the nature of the antigen(s), antigen presentation and the innate immune response. The role of these mechanisms in periodontal disease is reviewed and suggestions for future research are put forward.