CD4 and systemic lupus erythematosus: In vitro stimulation of TLR2 on SLE patient CD4+ T cells with a synthetic bacterial lipopeptide, Pam3-Cys-Ser-Lys4 (Pam3CSK4), significantly induces IL-17A and IL-17F production by upregulating H3K4 tri-methylation levels in the IL-17A promoter region and H4 acetylation levels in both IL-17A and IL-17F promoter regions [213].