Lymphocyte responsiveness to Pseudomonas aeruginosa in cystic fibrosis: Relationship to status of pulmonary disease in sibling pairs.

Lymphocyte proliferative responses to Pseudomonas aeruginosa and Staphylococcus aureus were evaluated in 
six sibling pairs with cystic fibrosis. In each pair, one sibling 
had advanced clinical disease, whereas the other sibling was in good 
clinical condition. Three in this latter group had no clinically apparent 
Pseudomonas bronchitis. In all cases, the average responses to Pseudomonas isolated 
from each sibling pair were lower in the sibling with advanced 
clinical disease. This difference was not observed in the responses to 
Staphylococcus. Normal plasma or plasma from patients with CF in good 
clinical condition does not restore the responses in patients with advanced 
clinical disease. However, plasma from patients with low or no responses 
to Pseudomonas inhibits the responses of responding siblings. A progressive specific 
lymphocyte unresponsiveness to Pseudomonas may play an important role in the 
increasing destructiveness of chronic pulmonary Pseudomonas infection in cystic fibrosis. 