The presence of functional CR3 is important in CD44-mediated phagocytosis. (A) Efficiency of phagocytosis of CD44 Ebabs and iC3b-opsonized erythrocytes by RAW macrophages preincubated with buffer control or blocking CR3 antibody or nonimmune isotype control antibody. * indicates different from the buffer only and nonimmune IgG2b (P < .05). Data are shown as the means plus or minus SE; n = 6. (B) Transmitted light image of human neutrophils binding iC3b-opsonized sheep red blood cells forming a rosette. (C) Efficiency of phagocytosis of CD44 Ebabs and isotype Ebabs by CD44^−/−, CD18^−/−, CD44^−/−/CD18^−/− (double-knockout), and wild-type peritoneal macrophages. * indicates different from wild-type peritoneal macrophages (P < .01). Data are shown as the means plus or minus SE; n = 6.