Background Cytokines production by T helper lymphocytes (Th cells), which orchestrate the interplay of the different cells involved in airway inflammation of asthma, may be reflected in peripheral blood. Some studies have suggested that the Th cell cytokines by peripheral blood T cells correlate with asthma severity.
Objective To investigate the relationship between changes in IFN-γ production by peripheral blood T cells and changes in lung function in chronic stable asthmatics.
Methods Sixteen patients with chronic stable moderate asthma aged 35–65 years (nine women) were recruited. Morning and evening peak expiratory flow rates (PEFR) monitoring and blood sampling for peripheral blood T cell culture, total IgE and blood eosinophils were performed at baseline and week 12. Levels of IFN-γ, IL-4 and IL-5 in culture supernatants of peripheral blood T cell were determined by using enzyme-linked immunosorbent assay (ELISA) kits.
Results Patients with increased IFN-γ changes from baseline showed significantly increased changes in morning (P = 0.02) and evening (P < 0.05) PEFR compared with those with decreased IFN-γ changes. The changes in IFN-γ production and IFN-γ: IL-4 ratio significantly correlated with the changes in morning PEFR (Rs = 0.59, P < 0.02; Rs = 0.63, P < 0.01, respectively) and tended to correlate with the changes in evening PEFR (Rs = 0.45, P = 0.08; Rs = 0.5, P = 0.05, respectively). The changes in IL-4 and IL-5 did not correlate with the changes in IgE and blood eosinophils, respectively.
Conclusions These findings suggest that IFN-γ may be associated with the alteration of lung function in asthmatics and play a role in the pathophysiology of chronic stable asthma.