Circulating CXCR5+CXCR3+PD-1Lo Tfh-like cells in HIV-1 controllers with neutralizing antibody breadth

HIV-1-specific broadly-neutralizing antibodies (bnAb) typically develop in individuals with continuous high-level viral replication and increased immune activation, conditions that cannot be reproduced during prophylactic immunization. Understanding mechanisms supporting bnAb development in the absence of high-level viremia may be important for designing bnAb-inducing immunogens. Here, we show that the breadth of neutralizing antibody responses in HIV-1 controllers was associated with a relative enrichment of circulating CXCR5+ CXCR3+ PD-1Lo CD4 T cells. These CXCR3+ PD-1Lo Tfh-like cells were preferentially induced in vitro by functionally superior dendritic cells from controller neutralizers, and able to secrete IL-21 and support B cells. In addition, these CXCR3+ PD-1Lo Tfh-like cells contain higher proportions of stem cell-like memory T cells, and upon antigenic stimulation differentiated into PD-1Hi Tfh-like cells in a Notch-dependent manner. Together, these data suggest that CXCR5+ CXCR3+ PD-1Lo cells represent a dendritic cell-primed precursor cell population for PD-1Hi Tfh-like cells that may contribute to the generation of bnAbs in the absence of high–level viremia. We analyzed transcriptional profiles of mDC from 4 neutralizer controllers compared to cells from 4 non-neutralizer controllers.