Advances in the physicochemical, immunologic and cytologic investigation of the synovial fluid.

Investigations of the pathologic synovial fluid (SF), carried out by numerous research teams, have attempted to elucidate certain pathogenic mechanisms suggestive for diagnosis and treatment. Recent studies have tried to draw some biorheologic patterns of the SF, useful for diagnosis and for the evaluation of certain therapies (synoviorthesis). A systematization of the microcrystalline arthropathies has been possible by microscopic examinations of the SF. Enzymologic studies have demonstrated the properties of enzymatic inhibitors of some classical antirheumatic drugs, suggesting the introduction of new antienzymatic products, and have supported the indication for synoviorthesis. Studies of the SF oligoelements have established new criteria for differential diagnosis, have suggested new treatments (by zinc compounds) and have offered explanations for the good effects of some drugs, such as D-penicillamine. Knowing the role of the toxic oxygen radicals in the pathogeny of the rheumatoid synovial inflammation, drugs with a protective action against the effects of free radicals have been introduced in the antirheumatic therapy. Analyses of the various SF cellular populations, including complex immunologic, cytoenzymatic, optic and ultrastructural cytologic investigations, are opening new prospects of clinical application. The general review of the above-mentioned problems is based on the personal experience of the authors and on the latest data in the specialty literature.