Decay of κCHEB LC upon conditional deletion by pI-pC. (A) PCR analysis of VκJκ CHEB deletion after pI-pC injection. PCR was performed on splenocytes DNA of killed mice at days 0, 4, and 10 after pI-pC injection. The 1.2-kb and 0.4-kb bands correspond to the undeleted and the deleted VκJκ gene, respectively, using 5′Jκ and 3′ Jκ primers indicated in Figure 1. M1 indicates pBS Hpa II ladder; M2, λ HIII/Eco RI ladder. (B) Flow cytometric analysis of B220-positive splenocytes at days 0 and 4 after the first pI-pC injection. Freshly isolated spleen cells were stained with anti-B220 and anti-κ fluorescent antibodies. Percentages of κ-positive and κ-negative B220-positive cells are indicated.