
<ArticleTitle>The <prot>epithelial cellular adhesion molecule</prot> (<prot>Ep-CAM</prot>) is a ligand for the <prot>leukocyte-associated immunoglobulin-like receptor</prot> (<prot>LAIR</prot>).</ArticleTitle>
<AbstractText>Human <prot>leukocyte-associated immunoglobulin-like receptor (<prot>LAIR</prot>)-1</prot> is expressed on many cells of the immune system and is predicted to mediate inhibitory functions based on the presence of immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in its cytoplasmic domain. Although the role of <prot>LAIR-1</prot> in the regulation of immune responses in vivo is unknown, <prot>LAIR-1</prot> cross-linking by monoclonal antibody inhibits various immune cell functions in vitro. Here, we identify the colon carcinoma-associated <prot>epithelial cellular adhesion molecule</prot> (<prot>Ep-CAM</prot>) as a ligand for <prot>LAIR-1</prot> and <prot>LAIR-2</prot>, a related soluble <prot>LAIR-1</prot> family member. <prot>Ep-CAM</prot> interacts with the <prot>LAIR</prot> molecules through its first <prot>epidermal growth factor</prot> domain; <prot>Ep-CAM</prot>--specific antibodies can abrogate the binding. Intraepithelial T lymphocytes express <prot>LAIR-1</prot> and thus may interact with <prot>Ep-CAM</prot> present on human intestinal epithelium. We propose that <prot>LAIR-1</prot>--<prot>Ep-CAM</prot> interaction may contribute to mucosal tolerance and that <prot>LAIR-2</prot> possibly modulates this function.</AbstractText>
