Additional notes on the use of analytic isoelectric focusing for the detection of cystic fibrosis protein in serum [letter].

In a previous communication, written in response to a letter by Smith 
et al., we suggested several possible reasons for the inability of 
Thomas et al. and other investigators to detect cystic fibrosis protein 
(CFP) using electrofocusing techniques. Thomas and coworkers communicated with us for 
the purpose of determining possible reasons for their inability to detect 
CFP by electrofocusing. Key points made during these conversations are reiterated 
below in a firm attempt to alleviate future problems by inexperienced 
investigators in their attempts to use analytic electrofocusing to detect CFP. 
In our communications with Thomas and coworkers we learned that, despite 
our suggestions, they had not analyzed the samples they screened by 
either using the equipment of Awdeh et al. or employing our 
standardized procedure. It is unknown whether or not they exercised the 
requirements for serum sample collection, processing, and storage. We feel the 
above reasons are sufficient to explain the reported failure of Thomas 
et al. to reproduce our results and to detect consistently a 
CFP in sera from individuals with the CF gene. 