Enzyme release from polymorphonuclear leukocytes during interaction with calcium oxalate microcrystals.

The interaction between polymorphonuclear leukocytes and calcium oxalate crystals results in enzyme release from the cells, due to exocytosis and plasma membrane damage. Positive charges on the crystals apparently play a predominant role in the interaction. Removal of negatively charged sialic acid from the cell surface has little effect on crystal-induced enzyme release. Glucose-loaded liposomes release glucose upon exposure to calcium oxalate crystals when the liposomes are negatively charged but not when the liposomes bear a positive charge. Cytoplasts, which are devoid of granules, are severely damaged by calcium oxalate crystals. As with intact cells the damaging effect of the crystals on liposomes and cytoplasts can be counteracted by a polyanion. The results are consistent with the view that calcium oxalate crystals can cause enzyme release from polymorphonuclear leukocytes, mainly by a direct effect on the plasma membrane. The release might be due to an interaction of positive charges on the crystals with negative countercharges on the cells, possibly located in the phospholipid bilayer.