Fig. 7.
CXCR5loICOSlo CD4+ T cells express large amounts of BCL6. (A) Expression of BCL6 and PRDM1 transcripts by tonsillar Th populations was analyzed by real-time RT-PCR. Expression of each transcript was normalized to that of HPRT1 transcript (n = 3). One-way ANOVA Bonferonni multiple comparison test. ***P < 0.001, **P < 0.01, and *P < 0.05. (B) Expression of Bcl6 and Blimp-1 proteins in tonsillar Th populations. Sorted Th populations were lysed, and equal amounts of protein were loaded per well to analyze the expression of Bcl6 and Blimp-1 by Western blotting. For the positive controls, the lysate of GC-B cells was used for Bcl6 detection, and BJAB (a B-cell line) cell lysate was used for Blimp-1 detection. Expected Blimp-1 band is indicated with an arrow. Densitometry score ratio for Bcl6 and Blimp-1 against control actin protein is indicated in number (a representative of four experiments). (C) Analysis of Bcl6 expression in tonsillar CD4+ Th populations by flow cytometry (a representative of four experiments). (D) Up-regulation of ICOS and PD-1. The four Th populations were cultured with naïve B cells, and the expression of ICOS and PD-1 on T cells was analyzed at day 5 (a representative from two experiments).