A recent study showed that HDAC2 expression was suppressed in pro-inflammatory CD8+CD28null NKT-like cells in patients with COPD (19) and negatively correlated with the percentage of CD8+CD28null NKT-like cells producing IFNγ or TNFα in all subjects (e.g., COPD: R = −0.789, p < 0.001 for CD8+CD28null NKT-like cells producing IFNγ) (Figure 2D). This evidence concerns the gene IFNG and chronic obstructive pulmonary disease.