Inhibition of proliferation/activation by competition is independent of antigen dose. (A) Diagrammatic representation of the experimental protocol. (B) Flow cytometric analysis of transferred B1-8^lo CD45.1⁺ CFSE-labeled B cells in draining lymph nodes 4 d after immunization. Gated on CD19⁺Igλ⁺CD45.1⁺. (top) Representative FAS/GL-7 plots. (bottom) Representative CFSE histogram. (C) Quantification of data in B. Each symbol represents one mouse. Data are from two independent experiments with two to three mice per condition per experiment.