Affinity and kinetic analysis of the molecular interaction of ICAM-1 and leukocyte function-associated antigen-1.
LFA-1 is a member of the beta2 integrin family, and interacts with ICAM-1, a member of the Ig superfamily containing five Ig-like domains. Interaction of LFA-1 with ICAM-1 is important in a number of cellular events, including Ag-specific T cell activation and leukocyte transendothelial migration, which are known to be typically transient and highly regulated. In this study, we have used surface plasmon resonance technology to study the ICAM-1/LFA-1 interaction at the molecular level. A soluble form of LFA-1 (sLFA-1), normally expressed as two noncovalently associated membrane-bound subunits, has been produced, and its interaction with ICAM-1 has been examined. The kinetic analysis of a monomeric sLFA-1 binding to the first two domains of ICAM-1 expressed as a chimeric IgG fusion protein (D1D2-IgG) revealed that sLFA-1 was bound to the D1D2-IgG chimera with a Kd of 500 nM and dissociated with a k(diss) of 0.1 s(-1). Monomeric membrane-bound LFA-1 purified from plasma membranes showed a similar kinetic to sLFA-1. These results suggest that the monovalent interaction between ICAM-1 and LFA-1 has a primarily high affinity and a slow dissociation rate constant as compared with other adhesion molecules, suggesting a potential mechanism for firm adhesion.
Tominaga
Y
Y
New Product Research Laboratories III, Daiichi Pharmaceutical Co., Tokyo, Japan.
Kita
Y
Y
Satoh
A
A
Asai
S
S
Kato
K
K
Ishikawa
K
K
Horiuchi
T
T
Takashi
T
T
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D016169:Lymphocyte Function-Associated Antigen-1; D011993:Recombinant Fusion Proteins; D018799:Intercellular Adhesion Molecule-1