In Co-OVA-immunized Foxp3-eGFP transgenic mice without asthma induction (scheme in Figure S1A in Supplementary Material), a subset of CD25−Foxp3+ T cells appeared in CD4+CD25− population (9% versus 0.9%) while the size of CD25+FoxP3+ tTreg population barely changed, suggesting that the Co-OVA protocol preferentially led to CD4+ T cell conversion to asTregs, without recruiting or expanding tTreg pool on site (Figures S1B,C in Supplementary Material). Here, CD4 is linked to asthma.