CCR6 and hepatocellular carcinoma: The expressions of ICOS, PD-1, CXCR3, CCR6, and CCR7, which are phenotypic markers for circulating Tfh cells [9, 11, 12, 29], were detected in CXCR5+CD45RA−CD4+ T cells in the HCC and HC groups (Figure 2A).