Dynamics of virus-specific CD8+ T cells in the human nasal cavity.

The nasal cavity is the entry site for respiratory viruses. Understanding how the nasal cavity sustains memory CD8+ T cell is essential for improving respiratory virus management and vaccine development. Here, we sampled CD8+ T cells from the upper nasal turbinate and peripheral blood of healthy adults. We analysed their transcriptomic profile and antigen specificity for respiratory (SARS-CoV-2, Influenza A) and non-respiratory (HCMV) viruses. Transcriptomic analysis revealed that nasal CD8+ T cells failed to upregulate STAT1 following TCR stimulation, potentially enabling clonal expansion despite the antiproliferative effects of IFN signalling. They also exhibited a cytotoxic, Th1-like profile with tissue-residency markers but lacked TCF7 expression, suggesting limited self-renewal capacity. The CD8+ T cell analysis of antigen specificity demonstrates that local nasal exposure is indispensable for virus-specific CD8+ T cell detection. Only SARS-CoV-2 and influenza-specific but not HCMV-specific CD8+ T cells were detected in the nasal compartment. However, their persistence over time in the nasal cavity appears linked to repetitive viral exposure. Our findings provide insights into the adaptations of nasal-resident CD8+ T cells and highlight challenges in eliciting durable nasal T cell immunity, with important implications for vaccine strategies against respiratory pathogens.