Background: Recurrent aphthous ulcerations (RAU) are common oral inflammatory lesions. Interleukin (IL)-8 is a pro-inflammatory cytokine of host response to injury and inflammation. Our recent study has found that measurement of serum IL-6 level can detect only 24% RAU patients with an abnormal serum level. In this study, we examined both the serum IL-6 and IL-8 levels in a group of RAU patients. The abilities of IL-6 and IL-8 to detect patients with an abnormal serum level were compared in order to find out whether IL-8 was a more sensitive serum marker than IL-6 in monitoring the disease activity of RAU.
Methods: In this study, we used a solid-phase, two-site sequential chemiluminescent immunometric assay to determine the baseline serum levels of IL-6 and IL-8 in 146 patients with RAU, 9 patients with traumatic ulcers (TU), and 54 normal control (NC) subjects. Eighty-two RAU patients, with the serum IL-6 or IL-8 levels higher than the upper limit of normal serum concentration, were treated with levamisole for 0.5-3.5 months, and their serum IL-6 and IL-8 levels were measured after treatment.
Results: We found that 25% (37/146) RAU patients, as well as 33% (20/61) major-type, 19% (13/69) minor-type, and 25% (4/16) herpetiform-type RAU patients, had a serum level of IL-6 greater than the upper normal limit of 4.7 pg/ml. In contrast, 60% (87/146) RAU patients, as well as 59% (36/61) major-type, 59% (41/69) minor-type, and 63% (10/16) herpetiform-type RAU patients, had a serum level of IL-8 greater than the upper normal limit of 8.7 pg/ml. In 82 RAU patients with the serum IL-6 or IL-8 levels higher than the upper limit of normal serum concentration, treatment with levamisole for a period of 0.5-3.5 months could significantly reduce the serum IL-6 level from 12.0 +/- 1.6 to 3.0 +/- 0.5 pg/ml (P < 0.001), and could significantly lower the serum IL-8 level from 70.9 +/- 11.2 to 13.8 +/- 3.1 pg/ml (P < 0.001).
Conclusions: Because measurement of serum IL-8 level can detect 60% RAU patients with an abnormal serum level, while measurement of serum IL-6 level can detect only 25% RAU patients with an abnormal serum level, we conclude that serum IL-8 level is a more sensitive marker than serum IL-6 level in monitoring the disease activity of RAU. Levamisole can modulate both the serum IL-6 and IL-8 levels in RAU patients. IL-8, like IL-6, is also a useful serum marker in evaluating therapeutic effects of levamisole on RAU patients.