Recombinant human erythropoietin, but not iron supplementation, improves anemia in rats with adjuvant-induced arthritis.

Pathophysiological and therapeutic properties of anemia in rats with adjuvant-induced arthritis (AA) were investigated. Both anemia and chronic inflammation were induced in rats by a single injection of Freund's complete adjuvant. This study confirmed other earlier data that these anemic rats with AA had reduced serum iron levels and that the anemia was characterized as mild, non-progressive, hypochromic, microcytic. In addition, our studies showed that these anemic rats had slightly but significantly enhanced erythropoietin titers, but not renal failure; there was no significant difference in blood urea nitrogen and creatinine levels in anemic and normal groups. The anemia in rats with AA was improved by recombinant human erythropoietin (r-HuEPO) at 30 and 100 U/kg/day, given i.v. for 5 days. In contrast, iron-chondroitin-sulfate colloid (10 mg/kg/day, i.v. for 5 days) failed to improve the anemia and to enhance the effects of r-HuEPO. These data suggest that anemia in rats with adjuvant-induced arthritis is distinguished, pathophysiologically and therapeutically, from iron deficiency anemia, hemolytic anemia, and renal anemia.