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ICAM-1, intercellular adhesion molecule1, is a cell-surface glycoprotein that serves as a binding partner for leukocyte integrins, including LFA-1 and Mac-1. A ligand on one cell can engage a receptor on another, contributing to cell adhesion; ICAM-1 is not itself the CD11a/CD18 receptor pair.

A 1987 reconstitution experiment made the interaction testable. Purified ICAM-1 was placed in artificial supported lipid bilayers. Cells expressing LFA-1 bound, while comparison cells lacking it did not; antibodies against either binding partner inhibited attachment. Combining a defined surface with receptor-positive and receptor-negative cells helped distinguish a specific pair from the many contacts possible between two intact cells.^[ref]

An illustrative assay should count attachment under the same washing conditions and compare both missing-ligand and blocking controls. Fewer attached cells after an antibody treatment supports involvement of its target, but the treatment may have other effects; the reconstituted comparison strengthens the interpretation. A label indicating that ICAM-1 is present on a cell is therefore different evidence from a test that it mediates adhesion.

Steven D. Marlin is a researcher whose work helped identify a molecular pair involved in cell adhesion. In a 1987 study with T. A. Springer, Steven D. Marlin tested whether purified ICAM-1 could bind biological cells carrying LFA-1.^[ref]

The investigators incorporated purified ICAM-1 into artificial supported lipid bilayers. Cells carrying LFA-1 bound, while the negative comparison cells did not. Antibodies against either partner inhibited the interaction when applied to the corresponding surface.^[ref]

Reconstitution narrowed the explanation. Adhesion between two intact biological cells might depend on many surface components; supplying one purified candidate in an artificial membrane reduced that complexity. Blocking each side independently then tested whether both identified proteins contributed to the measured attachment.