CXCL8 and periodontitis: As levels of IL-8 and IL-6 appears to be impacted by heavy smoking following periodontal therapy [3, 22] the aims of this prospective cohort study were to determine the influence of smoking on the presence and level of serum inflammatory markers and clinical measures in smokers with stage III and IV periodontitis, and to compare levels of serum cytokines in smokers and non-smokers following step I-III and 12-month step IV periodontal therapy, with particular emphasis on IL-6 and IL-8.