Identification of leucocyte surface protein interactions by high-throughput screening with multivalent reagents.

We describe a high-throughput screening system to detect interactions between leucocyte surface proteins, taking into account that these interactions are usually of very low affinity. The method involves producing the extracellular regions of leucocyte proteins with tags so that they can be bound to nanoparticles to provide an avid reagent to screen over an array of 36 similar proteins immobilized using the Proteon XPR36 with detection by surface plasmon resonance. The system was tested using established interactions that could be detected without spurious binding. The ability to detect new interactions was shown by identifying a new interaction between carcinoembryonic antigen-related cell adhesion molecule 1 and carcinoembryonic antigen-related cell adhesion molecule 8.