Figure 1. Expansion of Tfh cells in MRL/lpr mice.

(A) Splenomegaly in MRL/lpr mice. (B) Splenocytes were isolated from MRL/lpr and B6 mice. After staining, cells were first gated for CD4⁺ T cells, and the CXCR5⁺PD-1⁺ cells were analyzed with a CD4⁺ gate by flow cytometry. (C) The percentages of CXCR5⁺PD-1⁺ cells among CD4⁺ T cells (n = 6 for each group). (D) IL-21 mRNA expression in fresh isolated splenocytes was determined by real-time RT-PCR (n = 6 for each group). (E) Bcl-6 mRNA expression in fresh isolated splenocytes was determined by real-time RT-PCR (n = 6 for each group). (F) Sorted CD4⁺CXCR5⁺PD-1⁺ Tfh cells from MRL/lpr and B6 mice were cultured in the presence of anti-CD3 and anti-CD28 for 2 days, IL-21 mRNA expression was determined by real-time RT-PCR. Results shown are representative of at least three independent experiments. (G) Sorted CD4⁺CXCR5⁺PD-1⁺ Tfh cells from MRL/lpr and B6 mice were cultured in the presence of anti-CD3 and anti-CD28 for 2 days, Bcl-6 mRNA expression was determined by real-time RT-PCR. Results shown are representative of at least three independent experiments. (H) IL-21 expression in spleens was confirmed by immunohistochemical staining. Further magnification of the black-bordered box shows the predominance of IL-21⁺ lymphocytes. The scale bar represents 50 μm.