PBMCs from the periodontitis patients secreted higher levels of the cytokines, both spontaneously (IL-1ß p=0.0001; IL-18 p=0.09) and after exposure to H2S (IL-1ß p=0.03; IL-18 p=0.04), which is a new finding not previously reported. The gene discussed is IL18; the disease is periodontitis.