Immunogen sequence: NFTGPGDPDS IRCDTRPQLL MRGCAADDIM DPTSLAETQE DHNGGQKQLS PQKVTLYLRP GQAAAFNVTF RRAKGYPIDL YYLMDLSYSM LDDLRNVKKL G. CD18, also known as the integrin beta 2 subunit, is a 90-95 kDa type I transmembrane protein expressed on all leukocytes.