Fig. 1.

IbpA and IbpB activate a defined repertoire of human and mouse BCRs. (A) Flow cytometry plots show human CD19pos B cells stained with fluorescently labeled IbpA and IbpB (Left) and bar graph quantification collected from three individuals (Right). (B) Analogous flow cytometry plots for mouse CD19pos B cells stained with fluorescently labeled IbpA or IbpB (Left) and bar graph quantification (Right). (C) Immunoglobulin heavy chain repertoire of sorted human B cells. Each symbol represents the repertoire of the corresponding sorted B cell population. Total B cells indicate repertoire of all CD19pos B cells regardless of Ibp binding. (D) Analogous immunoglobulin heavy chain repertoire of sorted mouse B cells and mouse B cells. (E) Ca²⁺ flux analysis of human peripheral blood CD19pos B cells (Left) and mouse CD19pos splenocytes (Right) after in vitro stimulation with IbpA, IbpB, or anti-IgM. (F) Representative contour plots of transgenic B cells expressing a VH6 BCR show bright staining of CD19 B cells with IbpA (Left) or IbpB (Right). (G) Ca²⁺ flux analysis mouse CD19pos splenocytes expressing a transgenic VH6 BCR after in vitro stimulation with IbpA, IbpB, or anti-IgM.