Time course of knee-joint swelling in rats with AIA used to evaluate cytokine mRNA. Values are means (n = 4 to 6); vertical bars indicate the standard error of the mean. The disease is characterized by rapid onset of acute inflammation, a peak on day 1, and a transition to chronicity on day 6. **P ≤ 0.01 in comparison with day 0; ++P ≤ 0.01 in comparison with the preceding date. AIA, antigen-induced arthritis.