Plasma arginine esterase activity in cystic fibrosis of the pancreas.

Using a micro-method for the determination of plasma arginine esterase activity, we 
have investigated the values for soybean trypsin inhibitor (STI)-inhibited arginine esterase 
activity in patients with cystic fibrosis, obligate heterozygotes and age matched 
control individuals. The mean of STI-inhibited activity is lowest for cystic 
fibrosis patients while the mean for normal controls is the highest. 
The mean of STI-inhibited activity for the heterozygotes is midway between 
the values of the patients and the normal individuals. The deficiency 
of arginine esterase activity was statistically significant for both cystic fibrosis 
patients and heterozygotes. 