CCR6 and HIV infectious disease: In functional in vitro experiments (Fig. 4) we were able to replicate the proposed model of a constitutive down-regulation of functional MAIT cell markers (i.e. CD161, IL-18R, CCR6) and eventual loss of TCRVα7.2+CD4–CD3+ T cells by stimulation with bacterial antigens and pro-inflammatory cytokines in HIV infection [7].