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An original and easily reproducible technique for isolating and culturating mononucleated phagocytes from rheumatoid synovial fluid was used by the authors to study the synthesis of PGE2, PGF alpha 2 and TxB2 by macrophages taken from 16 patients with rheumatoid arthritis. The functional importance of these macrophages was evaluated by comparing their ratios of prostaglandin synthesis. PGE2 and TxB2 are released in large quantities and are increased after stimulation with zymosan. Two distinct cell populations having different biochemical characteristics were identified from these macrophages based on their capacity to synthesize prostaglandins. Prostaglandin synthesis was correlated with the clinical progression of rheumatoid arthritic disease as evaluated by Lee's index and the time required to loosen up morning joint stiffness in these patients. No correlation was found between prostaglandin synthesis and the quantity of synovial fluid in the affected joint. The first results of a pharmacological study evaluating the activity of non steroid anti-inflammatory drugs using this experimental model are presented here. The addition of indomethacin to culture medium produces dose-dependent inhibition of prostaglandin synthesis.

Macrophages from synovial fluid were obtained by joint puncture of patients with rheumatoid arthritis or non-rheumatoid exudative arthropathies. This fluid was subsequently centrifuged and the resulting cell pellet was recovered and distributed for in vitro culture (Falcon Petri dishes: 60 x 15 or 35 x 10). Cells were washed after 4 hours in culture to eliminate non-macrophagic cells. A second cell wash was effected 24 hours later to eliminate non-adherent cells. The culture medium employed was fetal calf serum MMP 119 (Gibco). The macrophagic nature of the cultured cells was ascertained by non specific esterase determinations (Burstone method) and estimation of the phagocytic index (using zymosan). This technique permits the conservation of viable monocytes in culture thus facilitating investigation of their metabolic activity (for example: prostaglandins, prostanoids or fatty acids) and the effects of anti-inflammatory agents.

The biosynthesis capacity of PGE2 and PGF2 alpha in normal and pathological (rheumatoid arthritis and osteo-arthrosis) synovialis was studied using the radio-immunological method, simultaneously on homogenized tissues and the microsome fraction, with or without addition of exogenous arachidonic acid. Among the results obtained, the most significant concern rheumatoid polyarthritis: a net increase in PGF2 alpha and especially in PGE2, more pronounced in the homogenized emulsion than in the microsomial fraction. Exogenous arachidonic acid increases the biosynthesis capacity of the PG. The prospective interest of this model is underlined: the possible introduction in the incubation medium of various drugs, making it possible to study the various factors taking part in the biosynthesis of PG (phospholipase A2 and prostaglandin-synthetase).

Prostaglandins (PG) are currently suspected to be involved in human rheumatoid arthritis (RA). We have studied the PG [PGE2, PGF2 alpha, and Thromboxane B2 (TXB2)] biosynthesis capacity of normal (from amputations) and pathologic (osteoarthritis (OA) and RA) synovia. The measurement is done on the whole homogenate and microsomal fraction after 40 min incubation, without exogenous arachidonic acid (AA) or with a saturating concentration (25 micrograms/ml) of this compound, using a radioimmunoassay method. There is a considerable increase in PGE2 and PGF2 alpha production by the rheumatoid synovia and more PGE2 and PGF2 alpha are formed. This production is more marked for homogenates than microsomal fraction. The OA group is not homogeneous and does not differ significantly either from normals or from RA. The addition of AA considerably increases the biosynthesis of PG in both normal and pathologic tissue. For TXB2, the first results (four synovia) show no or a small biosynthesis in RA as well as in normals. Nevertheless, the levels before incubation seem higher in RA than in normal tissue.