Figure 3.

Induction of phosphorylated form of GANP DNA-primase in activated B cells in vitro and in vivo. (A) Normal spleen B cells were stimulated in vitro for 48 h with the stimulatory reagents as indicated. GANP expression was detected by anti-GANP mAb, and the induction of phosphorylation at Ser⁵⁰² was detected by anti-pSer⁵⁰² (PG/103) mAb in comparison with a control anti-glutathione S-transferase mAb. (B) The spleen sections from the TNP-KLH-immunized mice were stained histochemically as described in Materials and Methods. (Left) Most of pSer⁵⁰² signal (blue) overlaps with PNA⁺ cells (brown). (Center) pSer⁵⁰² signal (blue) appears up-regulated selectively in GC-B cells surrounded with IgD⁺ cells (brown). (Right) The up-regulation of pSer⁵⁰² signal (blue) is detected in both CR1⁺ (brown) and CR1⁻ area of GCs. The sections were prepared by the serial manner so that the profiles of the multiple markers are to be superimposed.