Quantitation of eosinophil Major Basic Protein cytotoxicity to rodent respiratory epithelium.

Eosinophil Major Basic Protein (MBP) may be a potent effector in damaging airway epithelium and inducing acute (2-3 h) hyperresponsiveness to agonists in primates. Accordingly, interactions between human eosinophil MBP and guinea-pig airway epithelium were quantitated biochemically. MBP was extracted from human eosinophils and purified by size-exclusion HPLC. This resulted in a single protein band on electrophoresis, which cross-reacted with antisera raised to peptides derived from the predicted sequence of human MBP. This human MBP caused modest, but statistically significant, damage to respiratory epithelium (16.4% increase in efflux of 51Cr from guinea-pig tracheal rings) after 3 h of incubation with 10(-4) M concentration, but not with lower concentrations. These data demonstrates that MBP cytotoxicity to intact epithelium can be rapidly measured in vitro, and suggests that rodent airway epithelium may be relatively resistant to the cytotoxic effects of MBP.