The results of our study showed that TsEVs application in healthy mice stimulated the expression of IL-10 and TGF-β in CD4+ and CD8+ T cells, as well as the expansion of Treg cells, in both the lungs and spleen, and these effects were maintained in mice that were i.n. treated with TsEVs as a therapy for allergy. Here, CD4 is linked to allergic disease.