Anti-Sm B-cell development in spleen of 2-12H Tg, 2-12H MRL, 2-12H/Fas^lpr, and 2-12H MRL/Fas^lpr mice. (A) Anti-Sm B cells are present in the spleen of 2-12H Tg, 2-12H MRL, 2-12H/Fas^lpr, and 2-12H MRL/Fas^lpr mice. All histograms are gated on CD19⁺ B cells, and anti-Sm B cells are boxed. All mice are 2 to 4 months of age. (B) Numbers of splenic B cells and anti-Sm B cells are presented. Means ± SEM of 5 6-month-old mice of the indicated strain are plotted. Asterisks indicate a statistically significant difference (*P < .05 and **P < .01) from cell numbers of their nonautoimmune counterparts. Cell numbers at 3 months are not statistically different from those shown for 6 months (data not shown). (C) B-cell subset analysis of splenic anti-Sm B cells from 1-month-old and 3-month-old mice based on CD21 and CD23 expression. Anti-Sm B cells are gated as indicated in panel A. The CD21^hi, CD23^lo cells are MZ B cells, and the CD21^int, CD23^hi cells are FO B cells. The percent of total anti-Sm B cells for each subset is given. (D) Total number of anti-Sm MZ B cells from 1- to 6-month-old mice of each strain is given. Gating for anti-Sm B cells is as shown in panel A. Mean ± SE is plotted (n = 6). (E) Sm staining of MZ and FO B cells is shown. Gating on total MZ and FO B cells was based on CD21 and CD23 expression as indicated in panel B. The shaded regions are Sm staining of non-Tg B cells; the solid lines are Sm staining by B cells of their Tg counterparts.