Gamma delta T-cell fraction of peripheral blood is increased in recurrent aphthous ulceration.

Recurrent aphthous ulceration (RAU) is the most common oral mucosal disease. The etiology is unresolved but several studies have suggested a systemic immunoregulatory imbalance in the patients. The purpose of the present study was to assess possible signs of immunologic deficiency or activation of peripheral blood mononuclear cells in patients with RAU by flow cytometry using three-color immunofluorescent staining which has not previously been employed in this patient category. The population consisted of 13 and 14 otherwise healthy patients with active and inactive RAU, respectively, and 18 healthy volunteers with a negative RAU history served as controls. The most striking observation was an increased fraction of T-cell receptor (TCR)-gamma delta+ cells in patients with active RAU (median percentage 8.5) compared with controls (median percentage 2.8; P < 0.001) and patients with inactive RAU (median percentage 5.0; P < 0.01). The fraction of peripheral TCR-gamma delta cells has not previously been determined in patients with RAU but the increased figures during active disease might reflect an immunologic stimulation during exacerbation. The nature of the stimulus remains to be established, but recent studies suggest that varicella zoster virus and/or cytomegalovirus may be involved. The potential role of TCR-gamma delta cells in RAU lesions has not yet been investigated but appears to be an obvious issue for future studies.