Figure 4.

In the absence of CD154, the plasma cell marker BLIMP-1 is induced, but AID, which is required for Ig class switching and somatic hypermutation in Ig V-region genes is not. Mice were immunized with NP-CGG and killed B. pertussis and responses assessed 3 and 7 days after immunization. Closed and open circles, respectively, represent individual lymph node responses from wild-type and CD154-deficient mice. (a) The induction of BLIMP-1 mRNA is significantly higher by 7 days after immunization than in non-immunized controls. (b) Levels of AID mRNA expression are below the level of detection in the absence of CD154. Median values for each of the groups are included above the data points. Data are representative of at least two repeat experiments.