CD4 and infection: However, in HIV-1 controllers, CXCR5+CXCR3+PD-1low CD4+ T cells were associated with increased HIV-1 neutralizing antibody breadth (41) and in acute HIV infection, frequencies of CXCR3+ Tfh1 cells correlated positively with p24 plasma IgG titers at 1 year post infection (33).