Sodium Transport in Cystic Fibrosis Fibroblasts

To the Editor: Although they are exciting, the results reported by Breslow et al. in the January 1 issue* seem more directed toward the reproducibility of the drug-resistance and sodium-transport phenomena than toward their validity as markers for cystic fibrosis (CF). Apparently, 21 of the 24 fibroblast lines used in the sodium-transport studies had been classified previously as normal or abnormal by means of drug-sensitivity testing, whereas only the fibro-blast lines from three unaffected siblings were being evaluated for the first time. Likewise, in the blinded study in conjunction with my laboratory mentioned in the article, four normal and four. . .