FIGURE 7.
Cross-linking CD19 and CD32 on pre-established PCs does not inhibit Ig secretion. (A) CD19 or CD32 surface expression was measured on cultures of purified blood B cells on day 7. Total cells in culture (left panels). Gated on IgD− CD38hi PCs (right panels). (B) Purified B cells were stimulated with IL-21/anti-CD40/anti-IgM, and IgG production was measured on the days indicated. Black line: IgG levels over 21 d in the absence of inhibitor; blue line: test agent indicated was added at the initiation of culture, and IgG levels were assessed on day 7; red line: test agent indicated was added after ∼25% of B cells had differentiated into PCs on day 7, and IgG levels were assessed on days 10, 14, and 21. One of four independent studies is shown.