Abstract
CD4+ T follicular helper (TFH) cells support tailored B cell responses against multiple classes of pathogens. To reveal how diverse TFH phenotypes are established, we profiled mouse TFH cells in response to viral, helminth and bacterial infection. We identified a core TFH signature that is distinct from CD4+ T follicular regulatory and effector cells and identified pathogen-specific transcriptional modules that shape TFH function. Cytokine-transcriptional TFH programming demonstrated that type I interferon and TGFβ signaling direct individual TFH phenotypes to instruct B cell output. Cytokine-directed TFH transcriptional phenotypes are shared within human germinal centers, but distinct TFH phenotypes dominate between donors and following immune challenge or in antibody-mediated disease. Finally, we identified new cell surface markers that align with distinct TFH phenotypes. Thus, we provide a comprehensive resource of TFH diversity in humans and mice to enable immune monitoring during infection and disease and to inform the development of context-specific vaccines.