Relationship between Interleukin 4 and 12 and chronic periapical lesion size

Chronic dental periapical lesions resulted from chronic inflammatory response to the periapical tissues. Since T-helper (CD4+Y) cells are the prominent cells in these lesions, so the aim of this study was to determine the correlation between the concentration of IL-4 and IL-12 (most important cytokines for differentiation of T helper 2 and T helper 1 cells, respectively), and the diameter of chronic periapical lesions. Thirty-eight chronic periapical lesions were collected which 18 periapical lesions had diameter of ≥5 millimeter (case group) and 20 periapical lesions had the diameter <5 millimeter (control group). Tissue samples were cultured for 72 hours, then ELISA (Enzyme linked immuno-sorbent Assay) was used for determining the concentration of IL-4 and IL-12 in supernatant fluids. Mann-whitney U and Spearman correlation tests were used to analyze the data. IL-4 and IL-12 were found in all of samples. There was no significant difference between case and control groups regarding the concentration of IL-4, IL-12 and IL-4/IL-12. The only significant correlation was between IL-4 and IL-6 concentration without any regard to the diameter of lesions (P<0.001) (Spearman correlation coefficient= 0.593). It is concluded that in chronic periapical lesions, probably T helper 1 and T helper 2 cells participate in active phases of inflammation and tissue damage equally. This could be resulted from mixed population of bacteria in these lesions.