Degradation of rat or sheep glomerular basement membrane by rabbit neutrophils in vitro. The roles of proteinases, complement and oxygen-derived radicals.

An in vitro assay for assessing degradative action of neutrophils on basement membrane has been developed. Basement membrane adhering to the base of microtitre wells can be reacted with neutrophils allowing monitoring of the release of cell components or of isotope from labelled membranes. Using either sheep or rat renal membranes labelled with [3H]propionate it was shown that either rabbit anti-sheep basement membrane antibody or rabbit anti-rat nephrotoxic serum promoted degradation of the membranes by neutrophils from rabbits. Studies with proteinase inhibitors showed that the degradation was a result of proteolytic action. Comparisons of the effects of serum or plasma with the effects of heat-inactivated serum or plasma showed that complement did not increase degradative activity but did increase the exocytosis of lysozyme by the cells. Hydroxyl radical was the principal oxygen-derived metabolite produced by the cells but free radical scavengers had no effect on the extent of degradation effected by the cells.