CD20⁺B-cell depletion in NHPs. (A) CD20⁺ B cells were measured in serum over time (CD20⁺ B-lymphocytes mean). SGN-CD19B results in dose-dependent depletion of CD20⁺ B cells compared with control. Treatment groups are indicated by distinct symbols: vehicle control (red closed circles); 10 μg/kg (blue closed squares); 30 μg/kg (light green closed triangles); 100 μg/kg (purple open squares); 300 μg/kg (orange closed diamonds); and 600 μg/kg (green open circles). (B) Immunohistochemical staining of CD20⁺ B cells in spleen at day 11 and 113. Comparison is shown for untreated (left), 30 μg/kg SGN-CD19B (middle), or 250 μg/kg SGN-CD19B (right). At day 11, monkeys treated with 30 μg/kg or 250 μg/kg of SGN-CD19B showed moderate (upper middle) to marked (upper right) depletion. Recovery was evident by day 113 (lower middle and right panels). Original magnification ×10.