Fig. 1
Different requirements of the activation stimuli for naive and memory B cells to induce the maturation of human dendritic cells. a Experimental design. Immature DCs were cultured in medium containing GM-CSF and IL-4 for 48 h either alone (DCctrl) or co-cultured at a 1:1 ratio with CD27− naïve B cells or CD27+ memory B cells that were pre-activated by BCR (DCNaïve-B-pBCR or DCMemory-B-pBCR) or BCR + CD40 (DCNaïve-B-pBCR+CD40 or DCMemory-B-pBCR+CD40) stimulation. b–d Phenotypic analysis (% positive cells and mean fluorescence intensity MFI) of DCs for the expression of co-stimulatory (CD80, CD86, CD40) and antigen-presenting (HLA-DR) molecules and the maturation marker (CD83). Representative plots and the mean ± SEM of data from four donors. e The supernatants of DC–B cell co-cultures were analyzed for the levels (pg/mL) of the IL-6 cytokine and CCL22 chemokine (mean ± SEM, n = 4 donors). f DCs were purified from B cell–DC co-cultures by depleting B cells using CD20 microbeads. CD4+ T cells were co-cultured with DCs at various ratios for 5 days. DC-mediated CD4+ T-cell proliferation was determined by the [3H] incorporation assay. Values are presented as counts per minute (cpm). Data are the mean ± SEM from quadruplicate wells and are representative of two independent experiments. *P < 0.05; **P < 0.01; ***P < 0.001; ns not significant by one way-ANOVA
