CD38 and HIV infectious disease: The frequencies of CD38+ (Figure 4C,K), HLA-DR+ (Figure 4C,L), CD38+HLA-DR+ (Figure 4C,M), PD-1+ (Figure 4C,N), CTLA-4+ (Figure 4C,O), CTLA-4+PD-1+ (Figure 4C,P), and (CD28−CD57+) (Figure 4C,Q) DN Tregs were augmented during early HIV infection, and ART was unable to normalize their frequencies to the levels seen in non-infected controls.