Fig. 1

Identification of CD40-activated human B cells which produce high levels of interleukin-10 (IL-10). a Peripheral blood CD20⁺ B cells were stained for CD20, CD27, and CD38 and gated as previously shown [3]. A representative dot plot shows the CD27⁻CD38^lo naïve (N), CD27⁻CD38^Int pre-naïve (PN), CD27⁻CD38^hi transitional (T), and CD27⁺ memory (M) B-cell subsets (n = 50). b Representative contour plot showing the frequencies of IL-10-producing B cells measured by intracellular cytokine staining of naïve, pre-naïve, and memory B-cell populations following stimulation with CD154-L cells for 72 hours. c The frequencies of IL-10-producing B cells in B-cell subsets as described in (b) (n = 10, cumulative data from nine independent experiments). d Supernatants from cultures as described in (b) and (c) were tested for the presence of IL-10 by enzyme-linked immunosorbent assay (ELISA). e Frequencies of IL-10-producing pre-naïve B cells following stimulation with L cells with and without CD154 expression as described in (b) (n = 3, cumulative data from three independent experiments). f IL-10 production by pre-naïve B cells following stimulation with L cells with and without CD154 expression was measured from culture supernatants by ELISA as described in (e). **P < 0.01, ***P < 0.001. IFN-γ interferon-gamma, IL interleukin