Anti-CD11b In Vivo Antibody - Low Endotoxin (44) recognizes Human CD11b. Anti-Human CD11b recognizes the alpha subunit of the CD11b/CD18 complex, an alpha/Beta heterodimeric surface glycoprotein on human leukocytes (Mr 165-170 kDa). The CD11b/CD18 antigen belongs to the B2 integrin family. Other names include Mac-1, Cr3, MO-1 and C3bi receptor. The CD11b molecule functions as a receptor for C3bi complement, clotting factor X, fibrinogen and ICAM-1.