Abstract
Durability of T follicular helper (Tfh) cell responses is pivotal for generating high affinity antibodies. We characterized Tfh cell responses to HIV Env immunization longitudinally in non-human primates, analyzing >500,000 CD4+ T cells from 192 lymph node (LN) samples collected over 60 weeks, including >36,000 vaccine-specific Tfh cells. An escalating-dose priming regimen elicited higher and more sustained Tfh cell responses in LNs, compared with conventional bolus immunization. Multiple vaccine-specific germinal center (GC)-Tfh subpopulations, including interleukin (IL)4hi and IL21hi GC-Tfh cells, were continually present. Antigen-specific Tfh clones persisted within GCs for over 6 months, maintaining stable gene expression profiles and showing no signs of exhaustion. Vaccine-specific Tfh proliferation signatures were detectable for 27+ weeks after priming. Tfh subpopulations correlated with HIV Env-specific antibody and neutralization titers. Additionally, substantial Tfh clonal migration occurred between LNs. Thus, complex populations of GC-Tfh can enhance antibody responses and survive for 48 weeks in GC responses without new antigen delivery, with implications for immunization regimens.