Improved method for detection of cystic fibrosis protein in serum using the LKB multiphor electrofocusing apparatus.

We have developed an improved method for the detection of cystic fibrosis 
protein (CFP). The method employs the LKB Multiphor to electrofocus whole 
serum, instead of the apparatus used in previous studies. Two basic 
modifications were necessary: (1) a pH 2.5--10.0 gradient instead of a 
pH 5--10 gradient, and (2) constant power for focusing the serum 
proteins instead of constant voltage. The first modification ensured adequate dissolution 
of the CFP-IgG complexes (or other precursor complexes which may liberate 
CFP). The second modification ensured a linear gradient (between pH 3.8 
and pH 9.2), excellent resolution in the pH 8--9 region, and 
the separation of CFP within 2 hr without overheating of the 
gel. Electrofocusing with the LKB Multiphor permits the detection of CFP 
in as many as 24 serum samples per gel. Results obtained 
from the analysis of 31 cystic fibrosis, 28 obligate heterozygote carrier, 
and 28 normal control sera indicate that CFP can be reproducibly 
and accurately detected in sera using the LKB Multiphor. 