Detection of cystic fibrosis protein by electrofocusing [letter].

Wilson et al. reported a biophysical assay for cystic fibrosis that employed 
isoelectric focusing of serum proteins. Their work appeared to establish the 
presence of a definitive marker for CF serum in the form 
of a protein band that was not present in normal serum. 
We tried to repeat their work and found that the background 
color of the fresh electropherograms made it rather difficult to detect 
unequivocally the presence or absence of bands in the appropriate pH 
region in CF vs. control serum. However, when the gels were 
photographed using Kodak Panatomic X film and a Wratten 25 A 
red filter, the color response and contrast of the film eliminated 
this interference to a great extent and it was much easier 
to detect the putative band. We agree partially with the observations 
of Wilson and Fudenberg, but would like to stress that the 
technique is not a diagnostic test. 