CD4 and leprosy: It has also been observed in gingival tissue biopsies from lesions of patients with leprosy, saliva, and GCF [43, 45, 49, 50, 56–60]; it is secreted by CD4+ T cells, CD8+ lymphocytes, peripheral blood mononuclear cells, and natural killer (NK) cells, which are also related to periodontal bone loss [14, 26, 61, 62].