Panel A shows flow cytometry contour plots and bar graphs of germinal center (GC) B cells in mesenteric lymph nodes. The contour plots display CD24 and CD38 markers, with the x-axis representing CD38 and the y-axis representing CD24. The bar graphs show the percentage of GC B cells over time, with days post-infection on the x-axis and the percentage of total CD19 plus cells on the y-axis. Panel B presents similar data for Peyer's patches, with contour plots and bar graphs following the same format. Panel C includes bar graphs quantifying IgA antibody-secreting cells (ASCs) in Peyer's patches and lamina propria, with days post-infection on the x-axis and the number of IgA ASCs per 1x10 superscript 6 cells on the y-axis. Panel D shows bar graphs quantifying IgG ASCs in the same tissues, with the same axes as Panel C. The graphs compare sham-infected and Bb-infected mice, highlighting transient increases in GC populations and ASCs during infection.
Bb alters local B cell responses in the GI tract. (A and B) Top, representative flow cytometry contour plots of GC B cells, defined as CD24hi CD38low cells gated on CD19+ live singlet lymphocytes, in (A) mesenteric lymph node and (B) Peyer’s patches at 14 dpi with Bb- or sham-infected controls. Lower panels, quantification of GC B cells as the percentage of total B cells. (C) Quantification of IgA ASCs in Peyer’s patches and lamina propria at indicated dpi, as measured by the ELISpot assay. (D) Quantification of IgG ASCs in Peyer’s patches and the lamina propria at indicated dpi, assessed by ELISpot. Bars indicate the mean ± SEM; each symbol represents results from one mouse (n = 2–10 per group). Each time point represents an independent experiment (day 14: A and B; day 28: C and D), each performed twice. Statistical analyses were conducted using the Mann–Whitney U test; *P < 0.05, **P ≤ 0.01, and ns, not significant (P > 0.05); NA, data not available.