title: LFA-1- and ICAM-1-dependent homotypic aggregation of human thymocytes induced by JL1 engagement.
abstract: Cell-cell adhesion is essential for the appropriate immune response, differentiation, and migration of lymphocytes. This important physiological event is reflected in vitro by homotypic cell aggregation. We have previously reported that a 120 kDa cell surface glycoprotein, JL1, is a unique protein specifically expressed by immature double positive (DP) human thymocytes which are in the process of positive and negative selections through the interaction between thymocyte and antigen-presenting cells (APCs). The function of the JL1 molecule, however, is yet to be identified. We show here that anti-JL1 monoclonal antibody (mAb) induced the homotypic aggregation of human thymocytes in a temperature- and Mg2+-dependent manner. It required an intact cytoskeleton and the interaction between leucocyte function associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) since it was blocked by cytochalasin B and D, and mAb against LFA-1 and ICAM-1 which are known to be involved in the aggregation of thymocytes. Translocation of phosphatidylserine (PtdSer) through the cell membrane was not detected, implying that the molecular mechanism of JL-1-induced homotypic aggregation is different from that of CD99-induced homotypic aggregation. In summary, JL1 is a cell surface molecule that induces homotypic adhesion mediated by the LFA-1 and ICAM-1 interaction and cytoskeletal reorganization. These findings suggest that JL1 may be an important regulator of thymocyte development and thymocyte-APC interaction.
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Korea.
authors.forename: G K
authors.initials: GK
authors.lastname: Lee
authors.forename: K C
authors.initials: KC
authors.lastname: Jung
authors.forename: W S
authors.initials: WS
authors.lastname: Park
authors.forename: M C
authors.initials: MC
authors.lastname: Kook
authors.forename: C S
authors.initials: CS
authors.lastname: Park
authors.forename: H W
authors.initials: HW
authors.lastname: Sohn
authors.forename: Y M
authors.initials: YM
authors.lastname: Bae
authors.forename: H G
authors.initials: HG
authors.lastname: Song
authors.forename: S H
authors.initials: SH
authors.lastname: Park
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects; D002449:Cell Aggregation / Q000187:drug effects*; D005434:Flow Cytometry; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000494:pharmacology*; D007938:Leukemia; D016169:Lymphocyte Function-Associated Antigen-1 / Q000494:pharmacology*; D010718:Phosphatidylserines / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000378:metabolism*; D013696:Temperature; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C114952:JL1 antigen; D016169:Lymphocyte Function-Associated Antigen-1; D010718:Phosphatidylserines; D018799:Intercellular Adhesion Molecule-1