Interleukin-4, a T-helper 2 cell cytokine, is associated with the remission of periodontal disease

Interleukin-4 (IL-4), secreted mainly by T-helper 2 cells, is a key cytokine for the growth and proliferation of B lymphocytes. Previous studies have proved that IL-4 has an anti-inflammatory effect owing to its efficient inhibition of the production of proinflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha), IL-1 alpha, IL-1 beta, IL-6 and IL-8 by monocytes/macrophages. The aim of the present study was to assess the relation between clinical parameters and concentrations of IL-4 within gingival crevicular fluid from inflamed gingiva and periodontitis sites and, subsequently, after treatment of the periodontitis sites. A total of 60 subjects were divided into three groups based on gingival index (GI), pocket probing depth and clinical attachment loss (CAL): healthy (group 1), gingivitis (group 2) and chronic periodontitis (group 3). A fourth group (group 4) consisted of 20 subjects from group 3, 6-8 weeks after treatment (i.e. scaling and root planing). Gingival crevicular fluid samples collected from each patient were quantified for IL-4 using the enzymatic immunometric assay. The highest mean concentration of IL-4 was obtained for group 1 (99.39 +/- 49.33 pg/mL) and the lowest mean concentration of IL-4 was obtained for group 3 (15.78 +/- 21.92 pg/mL). The mean IL-4 concentrations for group 2 (64.34 +/- 39.56 pg/mL) and group 4 (68.92 +/- 42.85 pg/mL) were intermediate between the levels in healthy subjects and periodontitis subjects. The mean concentration of IL-4 decreased from periodontal health to disease. Thus, we suggest that type 2 helper T cell cytokine, as represented by IL-4, was associated with the remission or improvement of periodontal disease.