CD44 stimulation increases CR3 affinity. (A-D) Flow cytometric analysis of human monocytes. All samples were incubated with the antibody that recognizes the high-affinity state of CR3. (A) CTRL indicates nonstimulated cells. (B) CTRL Isotype indicates cells stimulated with the isotype antibody. (C) CD44 indicates cells stimulated with the CD44 antibody. (D) PMA indicates cells stimulated with 1 μM PMA. Data are representative of 3 independent experiments.