(a) Antibody-blocking analysis of homotypic cell adhesion of BMC cells. Morphological properties of BMC after treatment with a control nonblocking anti-β₂ MoAb (A), anti-_L (B), anti-_v (C), anti-₄ (D), as well as anti–ΙCΑΜ-1 (E) and anti–VCAM-1 MoAb (F) are shown. (b) Effects of anti-₄integrin and anti–VCAM-1 MoAbs on early phase of homotypic aggregation of BMC cells. The cells are pretreated by 10 μg/mL of human Ig, divided into effector cells (labeled with hydroethidine) and target cells (labeled with sulfofluorescein diacetate) at a 4:1 ratio, added to 1 μg/10⁶ cells of indicated MoAbs, and enumerated using a flow cytometric analysis. Data are reported as the percentage of total targets presented as conjugates. The conjugated percentage is shown in the top, right-hand corner of each panel.