Prdm1-CKO and control mice (6- to 8-week-old females) were immunized with NP-CGG, and spleens were collected at day 7 following immunization. cDCs (CD11c^hiMHCII^hiCD11b⁺) were purified by cell sorter and cultured for 4 hours, after which cells and supernatant were collected. (A) Transcript of cytokines were measured from the cells by qPCR, and (B) secreted cytokines in the supernatant were measured by MSD in 3 independent experiments (n = 4 for CTL and n = 5 or 6 for KO). (C) To measure the activation of the inflammasome pathway, transcripts of Nlrp3 in cDCs were measured by qPCR and caspase-1 activity was measured by FAM-FLICA in cDCs. Each dot represents an individual mouse, and the bar represents the mean (n = 4 for CTL and n = 5 for KO) from 3 independent experiments. (D) STAT3 activation in naive T cells was measured. Naive CD4⁺ T cells and DCs were prepared, and T cells were stimulated with control DCs (CTL) or BLIMP-1–deficient DCs (KO) or rmIL-6 for 15 minutes. Neutralizing Abs of IL-6/IL-1β or control IgG were added during the stimulation in the indicated conditions. After the stimulation, cells were fixed and p-STAT3 and total STAT3 were measured by flow cytometry. Representative histogram images are on the upper row. A red line was drawn based on T alone without stimulation. Each dot represents an individual animal, and the bar represents the mean from 3 independent experiments (n = 12). An unpaired 2-tailed Student’s t test (Mann-Whitney) was used for A–C and 1-way ANOVA with Dunnett’s correction was used for D.