Figure 7.

Analysis of the genes within cluster 39 with expression enriched in marginal zone (MZ) B cells. (a) The mean expression profile of all probe set intensities within cluster 39 over the 84 samples. (b) Heat map showing the mean expression intensity of each probe set in cluster 39. Each column represents the mean (log₂) probe set intensity for all samples from each source. Significant differences between groups were sought by analysis of variance. P-values for those genes that were expressed significantly (P < 0·05) by MZ B cells at levels > 2·0 fold when compared with the other cell populations. (c) The mean expression profile of probe sets representing S1pr1 (blue), S1pr2 (red) and S1pr3 (green) across the 85 samples. (d) Treatment of mice with the S1P receptor modulator FTY720 rapidly displaces MZ B cells (CD1d⁺ cells, red) from the splenic MZ. In control mice many MZ B cells (left-hand panel, arrow) are situated within the MZ adjacent to the ring of MADCAM1-expressing sinus-lining cells (green). Following treatment with FTY720 MZ B cells are displaced from the MZ and retained in the follicles (right-hand panel, arrow-heads). FO, B-cell follicle. (e) Comparison of the mean expression profile of probe sets representing Adam28 (light blue), Asb2 (red), Tspan15 (green) and Zc3h12c (dark blue) across the 85 samples. (a, b, c and e) Samples are grouped according to cell type and are arranged in order of presentation as listed in Table S1. For each cell population mean expression levels are presented and the number of replicates is indicated in parenthesis on the x-axis. Red-boxed area indicates the MZ B-cell data sets. Blue-boxed area in (e) indicates the germinal centre (GC) B-cell data sets. (f) Cartoon illustrating the putative functions of all the genes represented in cluster 39 in MZ B cells.