CD4 and Autoimmunity: Immunoregulatory cells—regulatory T-cells (Tregs) [cell phenotype can be defined as CD4+CD25+Foxp3+, Tregs hardly express CD127, so they can also be expressed by CD4+CD25+CD127low/− (Seddiki et al., 2006)], participate in this important regulatory mechanism through the secretion of anti-inflammatory cytokines, such as interleukin-10 (IL-10), interleukin-35 (IL-35), transforming growth factor beta (TGF-β), and cell-cell contact, to prevent the occurrence of chronic inflammation and autoimmunity (Campbell, 2015).