Innate lymphoid cells (ILCs) are antigen-independent immune cells that like T cells may drive pathology in asthma. It is, however, unclear if ILCs are associated with treatable asthma traits such as decreased lung function or eosinophilic inflammation.

Our aim was to investigate peripheral blood ILC and T cell populations in relation to lung function and blood eosinophil concentration to better understand their relation in asthma.

The study population consisted of 86 selected 25-26-year-olds with (N=40) and without (N=46) asthma from the Swedish BAMSE birth cohort. Clinical data, lung function measurements and blood samples were collected. 18-parameter flow cytometry was used to analyze ILCs, CD4+ and CD8+ T cells. Clinical characteristics were investigated by group-wise statistics and cell phenotypes were analyzed in relation to asthma traits (FEV1 and FVC z scores and blood eosinophil concentration) by linear regression.

Subjects with asthma had a higher prevalence of atopic diseases and sensitization. In the unstratified linear regression we observed that changes in ILC phenotypes, for example the percentages of CD117+, CD45RO+ and KLRG1+ ILC2s were significantly associated with blood eosinophil concentration (p<0.05). For FEV1 and FVC we predominantly observed associations with CD117+ and CD45RO+ T cells. In subjects with asthma, we observed significant associations between CD45RO+ ILC populations and FEV1, between CD45RO+ T cells and FVC, and between several parameters among both ILCs, and T cells, and blood eosinophil concentration.

In conclusion, ILC, CD4+ and CD8+ T cell subpopulations are associated with treatable asthma traits in young adults.