Correlation between FcRH1 levels with cell size, cell cycle status, and surface IgD, IgM, CD80, and CD86 expression in tonsillar B cells. Tonsillar B cells were purified as described in “Materials and methods” for 4-color immunofluorescent analysis. Naive, pre-GC, and GC populations were subdivided into the indicated R1 to R8 subsets for analysis. DNA content analysis was conducted after cell fixation in 100% ethanol, treatment with RNase A, and staining with propidium iodide (40 μg/mL). Subsequent analysis of the naive subpopulations was conducted but is not shown here because of insignificant variation. Shaded areas indicate staining with the indicated antibodies, while the unshaded areas show Ig isotope control staining.