Electrophoretic analysis of serum proteins in cystic fibrosis.

This study utilized isoelectric focusing and electrophoresis in an attempt to detect 
a cystic fibrosis (CF) serum factor(s), for which there is considerable 
indirect evidence. The method of isoelectric focusing in polyacrylamide gels (IEFAG) 
specified by Wilson et al. (53), as reproduced in our laboratory, 
did not enable the detection of a CF factor protein reported 
to focus near pH 8.4-8.5. Consequently, we employed our modified IEFAG 
techniques, which enabled us to demonstrate significantly enhanced resolution and striking 
heterogeneity in serum gamm-globulins. Despite the significant increase in the number 
of bands resolved by our methods, neither a difference at pH 
8.4-8.5 nor other differences throughout the alkaline pH range could be 
detected consistently in the CF and heterozygous sera. The two-step IEFAG/disc 
electrophoresis technique outline by Altland et al. (2), as reproduced in 
our laboratory, indicated that at least one small, cationic protein could 
be fractioned from all serum samples. Improvements in the method of 
disc electrophoresis resulted in the observation of numerous bands from some 
samples and of differences among the samples, but no protein band 
unique to the CF genotypes was observed. Our approach, employing different 
electrophoresis techniques and varying the conditions of sample analysis, should have 
increased the likelihood of detecting a protein or proteins specific for 
the CF genotypes. Despite the many variations in our approach, no 
consistently unique protein was observed in the CF or heterozygous sera. 
A CF serum factor cannot be readily demonstrated by the electrophoretic 
techniques described. The value of the "biophysical assay" and the "nonbiologic 
technique" reported in the literature is suspect, and the promise and 
applicability of these techniques as diagnostic tests for the CF gene 
should be carefully evaluated. 