Figure 7. TACI requires MyD88 to induce CSR in mice.
(a) MyD88-binding site (BS) in human or mouse TACI. Numbers, amino-acid positions; bold letters, identical amino acids; box, MyD88-binding site in the THC domain. (b) QRT-PCR of AICDA, Iγ1-Cγ1 and Iγ1-Cμ transcripts from WT (open bars) or MyD88 KO (solid bars) mouse B cells cultured for 4 d in the presence or absence of BAFF, APRIL or CpG DNA plus IL-4. Results are normalized to ACTB (encoding β-actin) mRNA; RE, relative expression compared to control (ctrl) unstimulated B cells. (c) ELISA of IgG1 and IgM from WT or MyD88 KO B cells cultured as in c for 8 days. (d,e) QRT-PCR of Iα1-Cμ and flow cytometric analysis of surface IgA from WT or MyD88 KO B cells cultured as in b for 48 h (Iα1-Cμ) or 5 days (IgA). (e) QRT-PCR of AICDA and Iγ1-Cγ1 from WT or MyD88 KO B cells cultured with a ctrl antibody or anti-TACI for 2 d. *P < 0.05, versus wild type (one-tailed unpaired Student’s t-test). The data presented summarize three independent experiments performed by pooling splenic naive B cells from three mice (error bars, SEM).