T cell cytotoxicity in cystic fibrosis: relationship to pulmonary status.

T cell cytotoxicity (CTL) to an allogeneic lymphocyte target was evaluated in patients with cystic fibrosis (CF) before and during pulmonary exacerbations (group 1) compared to another group of CF patients who had stable pulmonary disease activity during their two study periods (group 2). CTL activity was significantly decreased in group 1 subjects studied prior to their pulmonary flares and in group 2 CF patients compared to normal controls at effector:target ratios of 12.5:1 and 6.25:1 (p less than 0.05 and p less than 0.05, respectively). Furthermore, in group 1, CTL lysis was significantly decreased during pulmonary flares compared to before flares at the 25:1 and 12.5:1, effector:target, (p less than 0.05 and p less than 0.05, respectively). T suppressor cell activity as measured by effect on in vitro control B cell IgM synthesis was significantly increased during pulmonary flares (p less than 0.05). Diminished CTL may be partially responsible for persistent colonization of Pseudomonas aeruginosa in CF.