Diphenylamine reaction in chronic joint diseases.

Niazi and State (1948) found that protein-free precipitate of plasma or serum heated in a boiling water bath with Dische's diphenylamine reagent gave a dark purple colour in certain diseases, especially in malignancy and inflammatory diseases, such as rheumatoid arthritis, rheumatic fever, subacute bacterial endocarditis, empyema, and tuberculosis (Dische, 1929, 1930). The value of this diphenylamine reaction as an index of rheumatic fever activity has been attested by Ayala, Moore, and Hess (1951), Coburn, Moore, and Haninger (1953), Coburn and Haninger (1954), and Coburn, Bates, Hahn, and Murphy (1956), but opinions differ as to its value in chronic joint diseases (Cecchi and Ferraris, 1955; Fearnley, Purkis, de Coek, Lackner, and Meanock, 1955; F6rster and Schmid, 1955; Rother, 1955; Gamp, 1955). We have therefore analysed diphenylamine levels in chronic joint diseases, and have correlated them with the non-glucosamine serum polysaccharide and mucoprotein levels, to elucidate the relation between these three reactions.