IFNG and chronic obstructive pulmonary disease: There was however a trend for an increase in the production of IFNγ by CD28null/CD8+ NKT-like cells (but not CD28null/CD8- NKT-like cells) in patients with COPD compared with healthy controls (Figure 3).There was an increase in the percentage of CD28null/CD8+ NKT-like cells producing TNFα in patients with COPD compared with healthy controls (Figure 4).