Inhibition by 6-mercaptopurine of Polyarthritis Induced by Freund's Adjuvant.

Formation of granuloma and production of antibodies in guinea-pigs receiving egg albumen with Freund's adjuvant may be suppressed by cortisone (Fischel, Kabat, Stoerk, Skolnick, and Bezer, 1954). The arthritis induced in rats by Freund's adjuvant may also be prevented by treatment with cortisone (e.g. Houssay and Frangione, 1961; Pearson, Wood, and Waksman, 1961), pyrazolidines, salicylates, and sodium aurothiomalate (Newbould, 1963). Cortisone, for example, has nonspecific antiphlogistic properties, which cannot be excluded in evaluating the mechanism of the cortisone effect in the prevention of this adjuvant-induced arthritis. There are numerous studies in the literature of the preventive effect of 6-mercaptopurine (6-MP) in the primary and secondary immune responses in skin and renal homografts, protein antigens, experimental allergic encephalomyelitis, and intramyocardial injections of streptococci (Schwartz, Stack, and Dameshek, 1958; Meeker, Condie, Weiner, Varco, and Good, 1959; Schwartz and Dameshek, 1959, 1960; Schwartz, Eisner, and Dameshek, 1959; Calne, 1960; Hoyer, Condie, and Good, 1960; Thomas, Morton, Crane, and Gardner, 1961; Zukoski, Lee, and Hume, 1961; Pierce and Varco, 1962; Laufer, Ginsburg, Gery, and Davies, 1963). To obtain further information regarding the pathogenesis of the arthritis induced by Freund's adjuvant, the effect of 6-MP on the appearance of this experimental arthritis has been studied.