Changes in lymphocyte reactivity to Pseudomonas aeruginosa in hospitalized patients with cystic fibrosis.

In vitro lymphocyte proliferative responses to Pseudomonas aeruginosa (PA) and Staphylococcus aureus were studied in 38 patients with cystic fibrosis admitted for treatment of deteriorating pulmonary status. All patients were examined at admission and at least once after an average of 2 wk of treatment. Case history scores at admission and clinical responses to treatment were assessed independently. Patients were divided, according to their initial reactivity to PA, into low responder and responder groups. Twenty-nine patients were low responders to PA at admission. Eight of the patients in this group also had abnormally low responses to SA. After treatment, 10 patients became PA responders, whereas 19 had persistently low responses to PA. Nine of ten patients who subsequently died were in this persistently low responder group. Nine patients were responders at admission, and 8 remained in this category after treatment. These findings indicated that patients with cystic fibrosis have abnormal lymphocyte proliferative responses to killed bacteria. This dysfunction is acquired, and reversible in some patients in association with clinical improvement after intensive intravenous antimicrobial treatment. Once established, lymphocyte unresponsiveness may contribute to the progression of PA lung infection by impairing pulmonary macrophage activation by reactive lymphocytes.