Role of Anion Transport

Airway secretions of cystic fibrosis patients were found to contain high concentrations oftaurine, which decreased with antibiotic therapy during acute respiratory exacerbations. Taurine, in a 1:1 molar ratio with HOCl/OCl-, caused a 10-fold increase in the amount ofHOCI/OCI needed to induce cytotoxicity to the cat lung epithelial cell line, AKD. Although DMSO protected cells against HOCl/OC--mediated injury, the presence of an equimolar concentration of taurine with HOCI/ OC- prevented DMSO from protecting cells and sulfhydryl groups against oxidation, suggesting the formation of taurine chloramines. Spectral properties confirmed the formation of monochloramines and dichloramines. Chloride-free buffer, DIDS, and low temperature (4°C) each protected the cells against taurine/HOCI/OClP, indicating that taurine chloramine uptake through anion transport pathways was required to induce cytotoxicity. A molar excess oftaurine inhibited cytotoxicity, by decreasing taurine dichloramines and increasing the formation of less toxic taurine monochloramines. We con