A novel anti-CD18 mAb recognizes an activation-related epitope and induces a high-affinity conformation in leukocyte integrins.
Monoclonal antibody MEM-148 was previously shown to recognize CD18 chains in a free form unassociated within leukocyte integrin heterodimers, but yet it is paradoxically able to induce a high-affinity conformation in the native, cell surface expressed LFA-1 molecules. Our results based on kinetics of binding, immunoprecipitation and cell-aggregation experiments demonstrate that the mAb does bind to and stabilizes a specific conformation of LFA-1 heterodimers apparently distinguished by an increased affinity to its cellular ligand(s). A similar high-affinity conformation of LFA-1, in which the MEM-148 epitope becomes exposed, is induced also by a Mg2+/EDTA or low pH (5.5-6.5) treatments which may mimic physiologically relevant situations in normal or inflamed tissues. Thus, mAb MEM-148 is a novel valuable tool for detection and induction of specific conformations of human leukocyte integrins.
Drbal
K
K
Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Angelisová
P
P
Cerný
J
J
Hilgert
I
I
Horejsí
V
V
D000818:Animals; D000911:Antibodies, Monoclonal; D018821:CD18 Antigens / Q000737:chemistry / Q000276:immunology*; D002449:Cell Aggregation; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D006801:Humans; D016023:Integrins / Q000737:chemistry / Q000276:immunology*; D019169:Jurkat Cells; D007700:Kinetics; D007962:Leukocytes / Q000276:immunology*; D008213:Lymphocyte Activation; D016169:Lymphocyte Function-Associated Antigen-1 / Q000737:chemistry / Q000276:immunology; D051379:Mice; D008958:Models, Molecular; D011487:Protein Conformation
D000911:Antibodies, Monoclonal; D018821:CD18 Antigens; D000939:Epitopes; D016023:Integrins; D016169:Lymphocyte Function-Associated Antigen-1