Imbalance of SARS-CoV-2-specific CCR6+ and CXCR3+ CD4+ T cells and IFN-γ + CD8+ T cells in patients with Long-COVID.

Long-COVID (LC) is characterised by persistent symptoms for at least 3 months after acute infection. A dysregulation of the immune system and a persistent hyperinflammatory state may cause LC. LC patients present differences in activation and exhaustion states of innate and adaptive compartments. Different T CD4 cell subsets can be identified by differential expression of chemokine receptors (CCR). However, changes in T cells with expression of CCRs such as CCR6 and CXCR3 and their relationship with CD8 T cells remains unexplored in LC. Here, we performed unsupervised analysis and found CCR6 CD4 subpopulations enriched in COVID-19 convalescent individuals upon activation with SARS-CoV-2 peptides. SARS-CoV-2 specific CCR6 CD4 are decreased in LC patients, whereas CXCR3 CCR6 and CCR4 CCR6 CD4 T cells are increased. LC patients showed lower IFN-γ-secreting CD8 T cells after stimulation with SARS-CoV-2 Spike protein. This work underscores the role of CCR6 in the pathophysiology of LC.