ICOS and internet addiction disorder: The percentage of ICOS+PD-1+ cells among CD4+CXCR5+ Tfh cells was higher in patients with AD than in HC (Figure 3B); however, the percentage of CD4+CXCR5+PD-1+ICOS+ cTfh cells was higher only in EAD patients (i.e., not in IAD patients) than in HC (Figure 3C).