Activated circulating T follicular helper cells and skewing of T follicular helper 2 cells are down-regulated by treatment including an inhaled corticosteroid in patients with allergic asthma.

Background: CXCR5 T follicular helper (T) cells primarily promote B cells to produce an antigen-specific antibody through germinal centers (GCs). T cells exist in circulation, and circulating(c) T2 cells, a subset of cT cells, are able to help naïve B cells produce IgE in healthy individuals. Conversely, IL-10-producing regulatory B (Breg) cells inhibit an accelerated immune response.

Methods: We investigated the roles of cT cells and cBreg cells based on a T2 response in patients with atopic asthma (AA). Thirty-two patients with AA and 35 healthy volunteers (HV) were enrolled. We examined cT cells including their subsets, their expression of ICOS and PD-1, and cBreg cells by flow cytometry and their associations with clinical biomarkers. Plasma levels of CXCL13, which is a counterpart of CXCR5, were also measured using ELISA.

Results: In patients with AA, cT2 cells were increased and cT1 cells were decreased compared with those in HV. The expression levels of ICOS on cT and their subset cells were elevated and Breg cells were greatly decreased. The plasma levels of CXCL13 in patients with AA were significantly elevated and correlated well with the cT2/cBreg ratio. These cells were examined in 10 patients AA before and after inhaled corticosteroid (ICS) treatment. Interestingly, the percentages and numbers of T2 and ICOS cT cells declined after ICS treatment together with improvements in symptoms and clinical biomarkers.

Conclusions: The percentages and numbers of cT2 and ICOS cT cells might be useful as biomarkers of T2 typed airway inflammation in patients with AA.