The variability of skin test hypersensitivity reactions in cystic fibrosis and asthma.

Cystic fibrosis (CF) children had a greater variability of skin prick test 
response compared with asthmatic children, when the tests were performed on 
two occasions. This suggests that there is a different cause for 
the allergy in the two groups, perhaps because the asthmatics have 
a transient period of susceptibility to sensitization in infancy and the 
CF children a persistent vulnerability. Amongst the asthmatic children, clinical improvement 
was associated with loss of some skin prick test reactions, and 
clinical deterioration with an increase in the number of positive reactions. 
Thus continuing allergic reactions may maintain a mucosal defect, resulting in 
a persistence of susceptibility to allergen sensitization, and control of the 
reactions may re-establish normal mucosal defence mechanisms. 