The SIgA system and hypersensitivity in patients with cystic fibrosis.

A number of investigations have been used for the first time to 
examine the secretory IgA (SIgA) system in different body fluids from 
patients with cystic fibrosis (CF). Free J-chain was detected in all 
the sputum specimens examined. The isolated free secretory component (SC) from 
CF sputum differed in electrophoretic mobility from the SC isolated from 
normal human colostrum. In addition the free SC from some CF 
saliva formed precipitin lines of partial identity with normal human saliva 
or colostrum. A higher proportion of CF sera (33%) than of 
normal sera (10%) contained free SC. These investigations suggest that there 
may be some defect in the synthesis and/or the assembly of 
the SIgA immunoglobulins, which if confirmed, may help to explain the 
impaired Type I and Type III allergic manifestations in patients with 
CF. 