Background:CD18 is a 90-95 kD type I transmembrane protein also known as integrin b2 subunit, LFA-1 b subunit, and b2 integrin. CD18 non-covalently associates with CD11a, CD11b or CD11c. CD18 is expressed on all leukocytes. CD18 and associated a chains function in adhesion and signaling in hematopoietic cells.