Lung Tfh13 Differentiate from Lymph Node-derived Progenitor Tfh Cells to Sustain Allergic Antibody Responses

Introduction/Rationale: Allergic inflammation is driven by high-affinity IgE antibody production. We previously reported that during acute allergy, IL-13–expressing Tfh13 cells promote IgE responses in lung draining lymph nodes. However, as allergy progresses to a chronic state, IgE responses can be compartmentalized, with locally produced IgE maintaining inflammation in lung tissue. This led us to hypothesize that local interactions among lung-resident Tfh, Tfh13, and B cells contribute to chronic allergic inflammation.

Methods: To test this, we used genetically engineered mice and a house dust mite (HDM) sensitization–challenge model. Lung Tfh subsets were characterized by flow cytometry, single-cell RNA-seq, TCR-seq, spatial transcriptomics, and adoptive cell transfer. Conditional deletion of Tfh populations was used to define functional requirements for lung Tfh populations.

Results: Tfh and Tfh13 cells accumulated in allergic lungs, with Tfh13 comprising 5–25% of CD4⁺CXCR5⁺PD-1⁺ T cells and producing large amounts of type 2 cytokines. Single-cell RNA-seq showed that lung Tfh13 cells possess a distinct transcriptional program compared to LN Tfh13 or lung effector Tfh. However, TCR-seq linked Tfh13 cells to Tfh progenitor (Tfh prog) populations in lung draining lymph nodes. Adoptive transfer assays further confirmed that Tfh prog cells travel from draining lymph nodes to inflamed lungs, where they differentiate into IL-21–producing eTfh and Tfh13 cells. Spatial transcriptomics further show that lung Tfh populations have distinct positioning indicating exposure to unique environmental factors. Finally, conditional deletion of effector Tfh cells reduced GC B cell and HDM-specific IgG/IgE responses, and attenuated eosinophilic inflammation.

Conclusion: These findings define in situ differentiation of effector Tfh populations from LN Tfh prog precursor cells and that these cells contribute to local lung inflammation in the context of allergic airway disease.