Figure 10.

Transgenic B cells expressing the iglb12 heavy chain enter germinal centers despite competition from WT cells. Data from two experiments in which 4 × 10⁵ purified B cells from CD45.2⁺ iglb12 heavy chain transgenic mice were labeled with CTV and adoptively transferred retro-orbitally into WT CD45.1⁺ recipients 1 d before intraperitoneal immunization with 20 µg huIB2-C4b or control-C4b and 25 µg Sigma Adjuvant System. 14 d later, spleen and lymph nodes from individual mice were pooled and enriched for IB2-PE⁺ and CD45.2-biotin⁺ iglb12 heavy chain transgenic donor cells using anti-PE and anti-biotin microbeads before analysis by flow cytometry. (A) Representative flow cytometric analysis of live CD19⁺ CD3⁻ Gr-1⁻ F4/80⁻ B cells binding IB2-PE tetramers, but not isotype control PE594 tetramers. (B) Representative gating of GL7⁺ CD38⁻ germinal center B cells in the IB2⁺ population described in A. (C and D) Representative gating (C) and quantitation(D) of the frequency of CD45.2⁺ CD45.1⁻ donor B cells within the total IB2⁺ and IB2⁺ GL7⁺ CD38⁻ germinal center populations described in A and B. The percentages of cells within gates in A–C are from representative animals. The bars in D represent the mean from individual recipient mice (n = 6–7), and P values (*, P < 0.05) were determined using an unpaired two-tailed Student’s t test.