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.