FIGURE 1.

Mouse-specific anti-CD40 mAb 201A3 exhibited antagonist activity, but not agonist activity. (A) 201A3 was unable to induce CD86 expression on mouse primary B cells after 2 d of culture, as measured by flow cytometry, in contrast to a known agonist Ab, FGK45. (B) 201A3 blocked mouse B cell upregulation of CD86 in response to CD40L (1 μg/ml). MR1, the control hamster anti-mouse CD40L Ab, blocked CD86 upregulation but required >100 nM.