Calcium pyrophosphate and monosodium urate crystal interactions with neutrophils: effect of crystal size and lipoprotein binding to crystals.

"Small" (between 75-98% of crystals less than or equal to 10 microns) and "large" (between 81-93% of crystals greater than 10 microns) size fractions of monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate triclinic (CPPD) crystals were incubated with human neutrophils and crystal induced neutrophil cytolysis monitored by measuring the release of lactate dehydrogenase. "Small" size fractions of MSUM and CPPD gave higher percent lysis values than "large" crystals. The binding of high density lipoproteins (HDL) and low density lipoproteins (LDL) to the crystals was quantitated. HDL and LDL bound in significant amounts to both CPPD and MSUM and strongly inhibited CPPD and MSUM induced neutrophil cytolysis. We propose that HDL and LDL bound to MSUM and CPPD may play important roles in the regulation of gouty inflammation.