Arthritis score after preventive treatment of rat adjuvant arthritis (AA) with various anti-CD4 mAbs or PBS (controls) (means ± SEM; n = 6 for all groups). Arrows show the days of treatment (days -1, 0, 3, 6). Treatment with W3/25 and OX35 significantly suppressed AA from day 13 until day 30. In contrast, RIB5/2 accelerated the onset of AA by 2 days and led to significant improvement only in the late phase (from day 27). **P ≤ 0.01, *P ≤ 0.05, in comparison with PBS-treated rats. One representative of three experiments is shown.