Under the influence of antigen-presenting dendritic cells, naïve CD4+ T cells differentiate into TFH cells, which are marked by high expressions of CXCR5 and IL-21, and low expressions of CCR7, IFN-γ, IL-4, and IL-17 (Rasheed et al., 2006; Nurieva et al., 2008; Morita et al., 2011).