While reduced IFN-γ in CF samples is suggestive of a Th2 bias in CF PBMCs, we did not observe increased production of the Th2-associated cytokine IL-13 (S5 Fig.), nor did we detect any correlation between IFN-γ and IL-13 levels in response to PHA, SEB and PA Lo (data not shown). Here, IL13 is linked to cystic fibrosis.