CD14+ monocytes secrete a variety of cytokines, including TNF-α, IL-1β, IL-6, IL-8, CCL2, CCL3, and CCL5, compared to CD14− cells from GCF in patients with periodontitis [67], which suggests that CD14+ monocytes may be a source of CCL5 in GCF and gingival tissue in patients with periodontitis. This evidence concerns the gene CD14 and periodontitis.