Early costimulation with IFN-γ led to the up-regulation of CXCR3 expression. Sorted CXCR3^- peripheral blood B cells were activated with CD40L, IL-2, and IL-10 as described (bold lines). To some cultures, IFN-γ or IL-4 was added at day 0 or day 3 as indicated (thin lines). CD19⁺ B cells (left column) and CD38⁺⁺/CD20^-/CD19⁺ plasma cells (right column) were analyzed at day 8 of culture. Data shown are representative for one of more than four experiments (Table 1).