B cell ICAMs are required for selection of low-affinity B cell clones but not for B cells presenting high levels of pMHCII. (A) Flow cytometric plots and graph showing the fraction of adoptively transferred Igλ⁺ B1-8^lo CD45.1⁺ B cells in the GC compartment of IC-1/2^+/+ or IC-1/2^−/− chimeric mice, 7 d after NP-OVA immunization. Data are pooled from two independent experiments with a total of eight to nine mice per group. (B) Flow cytometric analysis of IC-1/2^+/+ and IC-1/2^−/− B cells in NP-OVA immunized chimeric mice (∼20% IC-1/2^−/− DEC205^+/+, ∼80% IC-1/2^+/+ DEC205^−/−) treated with either anti–DEC205-OVA or anti–DEC205-CS or PBS (controls) on day 5 after immunization with NP-OVA. The percentage of each B cell subset in the GC compartment 8 d after immunization was normalized to the percentage in the follicular compartment. Data are pooled from two independent experiments with a total of four to six mice per group. Each dot in the graphs represents a single mouse; lines represent the mean. (C) Analysis of the proportion of adoptively transferred IC-1/2^+/+ and IC-1/2^−/− B1-8^hi B cells within the GC compartment (CD38^low FAS⁺) over time in mice immunized with NP-OVA. Each dot in the graphs represents the mean ± SEM. Data represent one to two experiments with 3–11 mice total for each time point. ***, P < 0.0004; ns, not significant; two-tailed Student’s t test. Host mice in which the GC contained more than 70% endogenous B cells were excluded from the analysis.