Trypsin-binding immunoglobulin G in cystic fibrosis, allergic, and normal children.

Using a simple and sensitive radioassay, we have determined the frequency of trypsin-binding (TB) immunoglobulin G (IgG) as a function of age in cystic fibrosis (CF) patients, in allergic patients, and in control subjects. These IgGs appear during the 1st years of life. Their frequency is maximum between 3 and 20 years of age and decreases during adulthood. In allergic children TBIgG appears later than in CF children and the maximum frequency (32%) is intermediate between those observed in CF and in control children (66 and 19.6%, respectively). We suggest that an endogenous form of trypsin is involved in the phenomenon.