Expression of surface markers on blood mononuclear cells 48 hours after the administration of antibodies. Mice were injected with 300 mg of anti-CD44 (A), anti–VLA-4 (B), and anti-CD11a (C). Control mice received 300 mg of rat Ig. Cells were stained with the injected antibody and FITC–MARK-1 (control mice, dashed line; treated mice, thick line) to test the global expression of the surface antigen; or with FITC–MARK-1 alone (control mice, dotted line; treated mice, thin line) to detect the injected antibody bound to the cell surface.