FIG. 2.

Cyclin D3 is required for germinal center maturation but is dispensable for germinal center initiation. (A and B) WT and Ccnd3^−/− animals were immunized i.p. with SRBCs, and GC generation, as indicated by the presence of CD95⁺ GL7⁺ B cells, was assessed by flow cytometry 7 days postimmunization. (C and D) WT and Ccnd3^−/− animals were immunized i.p. with SRBCs, and GC initiation, as indicated by the presence of PNA⁺ B cells as a percentage of total lymphocytes (filled symbols) or as percentage of B220⁺ cells (open symbols), was assessed by flow cytometry 4 days postimmunization. (E and F) WT (•) and Ccnd3^−/− (▴) animals were immunized i.p. with SRBCs, and GC maturation, as indicated by GL7 and IgD profile of PNA⁺ B cells, was assessed by flow cytometry 4, 7, and 10 days postimmunization. The data shown represent two independent experiments with three to five animals per group (A to D) or three animals per group (E and F) per time point. Graphs show means and SEM, along with the P value, as determined by using an unpaired t test.