Differences in the binding of blocking anti-CD11b monoclonal antibodies to the A-domain of CD11b.
CD11b/CD18 (Mac-1) is a leukocyte integrin that plays a critical role in neutrophil adhesion and the initiation of acute inflammatory responses. Several Mac-1 blocking mAbs bind to the A-domain of CD11b, a approximately 200 amino acid region in the N-terminal portion of the protein that is involved in ligand binding and Mac-1 functional activity. We examined several CD11b blocking mAbs for different patterns of binding to A-domain. We used human/murine chimeric CD11b expression constructs and deletions of the A-domain to examine binding. We describe the binding characteristics of mAbs 60.1, LM2/1, LPM19C, M170, 44, and 904. All of these mAbs, except for 60.1, bind to the C-terminal half of the human A-domain (CD11b181-316). mAb 60.1 was unique in that it required regions of the N- and C-terminal ends of the A-domain for binding. mAbs 60.1, LPM19C, 904, and 44 all required the A-domain to be intact for binding. This suggests that these CD11b mAbs recognize a conformational epitope. LM2/1 was capable of binding to a fragment of the A-domain, CD11b285-300. Inasmuch as this system has been used to define different mAb binding sites, it may be used to analyze specific ligand binding sites in the A-domain of CD11b.
Violette
S M
SM
Repligen Corporation, Cambridge, MA 02139, USA.
Rusche
J R
JR
Purdy
S R
SR
Boyd
J G
JG
Cos
J
J
Silver
S
S
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001665:Binding Sites / Q000276:immunology; D001667:Binding, Competitive; D002461:Cell Line, Transformed; D017353:Gene Deletion; D018014:Gene Transfer Techniques; D006801:Humans; D016177:Macrophage-1 Antigen / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000276:immunology; D016415:Sequence Alignment
D000911:Antibodies, Monoclonal; D016177:Macrophage-1 Antigen; D011993:Recombinant Fusion Proteins