Fig. 4.

WT B cells preferentially populate the GC when T cells specific for a peptide presented better by WT cells are available to provide help. (A) B1-8 B cells present OVA peptide better than B1-8.H2-O^−/− B cells to OT-II T cells. B1-8 and B1-8.H2-O^−/− mice were primed in vivo by immunization i.p. with NP-OVA. Forty-eight hours later, level of OVA presentation was measured by incubating titrated numbers of purified and irradiated NP⁺B1-8.H2-O^−/− and WT B cells with purified OT-II T cells. T cell proliferation was determined by [³H]thymidine incorporation during last 18 h of culture. Data are representative of four independent experiments. (B–D) Mixture of splenocytes containing equal numbers of NP⁺ B cells from B1-8 and B1-8.H2-O^−/− mice were transferred into B6 hosts, along with either Eα-specific TEa (control) or OVA-specific OT-II T cells, and mice were immunized with NP-OVA. Ten days later, GC composition was examined. (B) Contribution of each donor to donor-derived Ag-specific GC population. (C) Quantification of data shown in B for multiple mice. (D) Ratio of H2-O^−/− to WT B cells, normalized to ratio in transferred mixture, for the populations shown in B. Statistical significances were calculated using two-tailed paired t test for C and a two-tailed unpaired t test for A and D.