Aim: To identify cell lines expressing the putative ligand(s) for LAIR-1 and LAIR-2.
Methods: CHO cell lines secreting LAIR-1-Fc or LAIR-2-Fc fusion protein were prepared and the supernatants from the CHO cell lines were collected and purified by protein A affinity chromatography column. Several cell lines were stained with the purified LAIR-1-Fc and LAIR-2-Fc fusion proteins and then analyzed by flow cytometry for detecting the expression of their putative ligand(s). To exclude non-specific binding between the cells and the fusion proteins, the cell lines expressing their putative ligand(s) were pre-incubated with the mAbs against LAIR-1 or LAIR-2, stained with the fusion proteins, and analyzed by flow cytometry.
Results: Both LAIR-1 and LAIR-2 fusion proteins bound strongly with human amnion-derived epithelial cell line WISH, and moderately with human melanoma cell line C32, human embryo kidney epithelial cell line 293T, and human umbilical vein endothelial cell line ECV304. Furthermore, this binding could be blocked by the mAb FMU-LAIR-2.2 (recognizing both LAIR-1 and LAIR-2) or mAb FMU-LAIR-2.1(recognizing LAIR-2).
Conclusion: The putative ligand(s) for LAIR-1 and LAIR-2 were expressed on WISH, C32, 293T and ECV304 cell lines. LAIR-1 and LAIR-2 may share the same ligand(s). These findings lay the foundation for the molecular cloning of the putative ligand(s) for LAIR-1 and LAIR-2.