Characterization and membranolytic effects of triclinic calcium pyrophosphate dihydrate crystals

The effects of incubation time and buffers of differing phosphate concentration on the ability of well characterized, synthetic triclinic calcium pyrophosphate dihydrate (CPPD) crystals to cause hemolysis of erythrocytes were determined. Maximum hemolysis was attained between 8-11 h; the percent hemolysis was 79% at a high crystal concentration of 50 mg/ml. The percent hemolysis values decreased with increasing phosphate concentration, which may have been due to adsorbed phosphate ions partially masking or protecting the erythrocyte membrane from a binding interaction with CPPD crystals. CPPD crystals possessed a significant negative surface potential, and we postulate that the CPPD crystal-membrane interaction may be mediated via an electrostatic mechanism.