CD8+ T-cells producing IFN-γ (type 1 CD8+ T-cells) may also contribute to asthma symptoms and to asthma exacerbation in individuals suffering already from asthma [40], and this in spite of the fact that in early life they may protect against asthma development, by eliminating allergen-specific Th2 cells. This evidence concerns the gene IFNG and asthma.