Interleukin-1 β, interleukin-12 and interleukin-18 levels in gingival fluid and serum of patients with gingivitis and periodontitis

Introduction: Cytokines are of major importance in periodontal disease progression. Interleukin-12 (IL-12) stimulates interferon-gamma production by T helper type 1 (Th1) cells while IL-18 induces Th1 responses when present with IL-12 but Th2 responses in the absence of IL-12. IL-1 beta has been correlated with periodontal disease destruction. This study determined the local concentrations of these cytokines in sites of gingivitis and periodontitis. Methods: Gingival crevicular fluid was collected from two sites in each of 10 gingivitis patients and from two gingivitis sites and two periodontitis sites from each of 10 periodontitis patients. Serum samples were also collected. IL-1 beta, biologically active IL-12 p70, the IL-12 p40 subunit and IL-18 concentrations were determined by enzyme-linked immunoabsorbent assay. Results: IL-1 beta and IL-18 concentrations were higher in the gingival crevicular fluid from periodontitis patients than in that from gingivitis patients; IL-18 concentrations were higher than those of IL-1 beta. Very little IL-12, either p40 or p70, was detected in the gingival crevicular fluid samples. In the serum, very low levels of cytokines were found. The level of serum IL-12 p40, however, was higher than in the fluid from periodontitis sites of periodontitis patients. Conclusion: The local production of IL-1 beta and IL-18 in the gingival crevicular fluid increased with increasing inflammation and IL-18 was the predominant cytokine at both gingivitis and periodontitis sites. Very little IL-12 was detected with levels decreasing with increasing inflammation. These results suggest that there is an association between severity of periodontal disease and levels of IL-1, IL-12 and IL-18.