Natural killer cell function and number of peripheral blood are not altered in recurrent aphthous ulceration

Natural killer cell activity against K562 target cells was measured during active disease (within 48 hours after symptom debut, day 0), and in remission stages (days 14 and 28) of 10 patients with recurrent aphthous ulceration. Ten healthy sex- and age-matched persons with a negative history of recurrent aphthous ulceration served as controls. Baseline, interferon-alpha- and interleukin-2-boosted natural killer cell activity was not significantly different between patients and controls at any of the three time periods. Furthermore, the percentages of peripheral CD16+, CD56+, and CD14+ cells were at no time significantly different between patients and controls. This study supports other investigations with respect to a systemic T-cell imbalance in which a decreased CD3+ and CD4+ fraction is encountered among patients with recurrent aphthous ulceration; however, the previously reported increase in the CD8+ subsets was not confirmed in the present study. Although no quantitative or nonspecific functional alterations of circulating peripheral natural killer cells were observed in patients with recurrent aphthous ulceration, this does not preclude NK cell involvement in the lesion sites. Furthermore, with recent studies that suggest a possible implication of varicella zoster virus or cytomegalovirus in recurrent aphthous ulceration, studies of varicella zoster virus and cytomegalovirus specific killer activity in this patient population are hereby encouraged.