Humoral immune response to tetanus toxoid.

(A) Five fVIII-injected controls (■), 5 anti-CD40L–treated/nontolerant mice (●), and 7 anti-CD40L–treated mice tolerant to fVIII (♦) were injected intraperitoneally with 2 flocculation units of TT vaccine 5 weeks after the last challenge with fVIII. (B) Five control mice (■) injected 3 times with fVIII alone and 5 mice treated with fVIII plus anti-CD40L Ab (●) were immunized with TT 7 weeks after treatment. Results show the end-point titer of each sample, and the line is the mean for each group.