AIA was induced in 39 DA rats with the use of Freund's complete adjuvant. Rats received either 7.3 or 20 mg/kg of muIL-17R:Fc or phosphate buffered saline intraperitoneally every other day from the time of arthritis induction for ∼17 days. Paw volume, arthritis severity, and weight were assessed every 3–4 days. Rats were killed between days 21 and 23 postinduction. Ankles were removed for quantitative radiology and histology and for immunohistochemistry for T cells.