Consistent with our observation that S100A9 and S100A8 are under-expressed in CD4+ T-cells from asthmatics, knock-out mice for S100A9 were shown to have increased Th2 cytokine levels and impaired Treg-mediated suppression of lung inflammation, compared to wild-type, after being challenged with the extracts from the allergenic mold Alternaria alternata21. Here, CD4 is linked to inflammatory response.