Letter: Plasma arginine esterase activity in cystic fibrosis.

We assayed the serum of a group of cystic fibrosis patients that 
were on oral arginine therapy and that of a group of 
cystic fibrosis patients that were not receiving this treatment for total 
arginine esterase activity. The untreated cystic fibrosis patients have significantly lower 
serum arginine esterase activity than the normal controls, the cystic fibrosis 
carriers, and the cystic fibrosis patients receiving oral arginine therapy. There 
is no significant difference between the arginine esterase activity of the 
normal controls and the cystic fibrosis carriers or the cystic fibrosis 
patients treated with arginine. - We have recently observed differences in 
the arginine esterases in plasma of controls and patients by electrofusing 
on polyacrylamide gels. Six activity bands could be detected in plasma 
of controls, whereas only five could be detected in plasma of 
patients. Our work on the deficiency of trypsin-like activity in mixed 
saliva of patients with cystic fibrosis has been reproduced by another 
laboratory. Coburn recently confirmed our work on deficiency of arginine esterase 
in serum of patients with cystic fibrosis. At present, the deficiency 
of arginine esterase in cystic fibrosis is a working hypothesis to 
understand the basic defect. - The variations of pH and sodium 
chloride content that I employed had been tested by me in 
6 patients both with and without a diagnosis of cystic fibrosis 
and were found not to alter the level of arginine-esterase activity. 
The major differences between the two studies resulted from the control 
subjects. Dr. Rao neglects to mention the few other laboratories that 
were unable to confirm his findings. 