IL1B and periodontitis: The primary aim of the present study was to investigate the secretion of IL-1β and IL-18 from PBMCs of periodontitis patients and healthy controls after exposure of the cells to H2S. A second aim was to measure the capacity of subgingival bacteria to degrade cysteine and produce H2S, and to test the association between this H2S production and inflammation in the gingiva.