CD4 and HIV-1 infection: In addition, the higher the frequencies of CD69-expressing TIGIT+NK and TIGIT−NK cells, the fewer CD4 T-cell counts were found in acute HIV-1 infection (TIGIT+NK: r = −0.49, P = 0.002; TIGIT−NK: r = −0.50, P = 0.002) and chronic HIV-1 infection (TIGIT+NK: r = −0.35, P = 0.037; TIGIT−NK: r = −0.41, P = 0.012).