Prostaglandin (PG) E2 generation by cultured canine synovial fibroblasts exposed to microcrystals containing calcium

Immunoreactive prostaglandin (PG) E2 was released into the ambient medium in a dose dependent fashion when either hydroxyapatite (HA) or calcium pyrophosphate dihydrate (CPPD) crystals were added to canine synovial fibroblasts in tissue culture. PGE2 release peaked 6 to 9 hours after HA or CPPD crystals were added in the presence of serum but at 24 hours if they were added in the presence of lactalbumin hydrolysate. PGE2 release correlated with crystal endocytosis estimated qualitatively by serial phase contrast microscopy and time lapse photography. As postulated previously by others for monosodium urate crystals, prostaglandin production by synovial cells may also be related to the pathogenesis of the destructive arthropathies associated with HA or CPPD crystals.