CD38 and HIV infectious disease: Of note, the expression of the HIV coreceptor CCR5 was greatly increased within CD38+CXCR3+ Tfhs (P < 0.0001) in the three study groups (67% in HIV-uninfected, 55.8% HIV-infected ART treated individuals and 44.5% in HIV-infected viremic individuals) (Figure 2C), suggesting that this subset might potentially be more susceptible to HIV infection.