| Autor: |
V. T. Moy, K. W. H. Chan, Elaine M. Hanson, B. A. Lollo, Adrienne A. Brian |
| Rok vydání: |
1993 |
| Předmět: |
|
| Zdroj: |
Journal of Biological Chemistry. 268:21693-21700 |
| ISSN: |
0021-9258 |
| Popis: |
Lymphocytes activated by antigen receptor cross-linking or phorbol esters adhere avidly to surfaces bearing intercellular adhesion molecule 1 (ICAM-1) through the adhesion receptor lymphocyte function-associated antigen 1 (LFA-1). It is not known whether avid adhesion by stimulated lymphocytes is due to higher affinity binding of ICAM-1 or due solely to post-receptor mechanisms. We have used a recombinant, soluble form of the ICAM-1 molecule to measure the affinity of binding to LFA-1 on unstimulated T cells and T cells stimulated with phorbol esters. The affinity was found to be too low for direct measurements, requiring instead the use of competition protocols in which ICAM-1 competes for binding with radiolabeled Fab from a monoclonal antibody specific for LFA-1. By analysis of the equilibrium and kinetics of competitive binding, we found that the affinity on unstimulated T cells is very low, about 100 microM. Activation of the T cells by phorbol esters caused a small increase in average binding affinity. Further analysis suggested that the change in average affinity reflected the conversion of a fraction of LFA-1 molecules to a state with a 200-fold higher affinity. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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