Decreased cell surface charge in cystic fibrosis epithelia.

A colloid titration technique has been used to determine the surface charge of cystic fibrosis (CF) and corresponding non-CF epithelial cells. We have shown that the negative surface charge of CF epithelial cells is significantly reduced in comparison with non-CF cells. This fact may play an important role in CF, where the increased adherence of microorganisms is known to cause chronic lung infection. Neuraminidase treatment removed approximately the same amount of surface charge in both cell lines, indicating no differences in cell surface sialylation. Similar results were obtained by direct measurements of the amount of N-acetylneuraminic acid released by neuraminidase. Therefore, our results indicate that sialic acid residues are not involved in the reduction of the negative surface charge in CF. This conclusion does not support the hypothesis that undersialylation of cell-membrane molecules occurs in cystic fibrosis.