Trypsin-binding IgG in cystic fibrosis.

It has been observed that most cystic fibrosis patients lack an alpha2 
macroglobulin-protease complex and that binding of trypsin and other proteases to 
alpha2 macroglobulin is lower in plasma of CF patients than in 
that of normal controls. We therefore decided to study the interaction 
of trypsin with plasma proteins of CF patients. Here we report 
that trypsin-binding IgG (TbIgG) is present in 80% of CF patients 
and in 30% of their mothers, but not in 97% of 
normal controls or in other relatives of CF patients. Experimental evidence 
supports the antibody nature of TbIgG, which is presumably produced against 
the porcine trypsin ingested by CF patients as pancreatic extracts for 
substitutive enzyme therapy. 