title: Characterization of activated lymphocyte-tumor cell adhesion.
abstract: This study demonstrates the variable expression of ICAM-1 and leukocyte function antigen-3 (LFA-3) on four tumor cell lines (COLO526, K562, Daudi, and HT-29). In addition, phorbol ester (PMA) activation of lymphocytes modulated LFA-1 from a uniform to a clustered surface distribution; whereas after treatment with high levels of Mg2+ ions, the unique epitope for high-affinity LFA-1 was identified using clone Mab24. Using a flow cytometric adhesion assay it was demonstrated that PMA-activated lymphocytes formed conjugates with COLO526 and Daudi, and that these conjugates were inhibited by anti-CD2 with varying inhibition by LFA-1 clones MHM24 and 25.3.1. When lymphocytes were induced to express the high-affinity form of LFA-1, conjugates were identified with COLO526, K562, and Daudi and these conjugates were sensitive to the presence of both CD2 and LFA-1 antibodies. Further studies using confocal microscopy confirmed significant adhesion between peripheral blood lymphocytes pretreated with either PMA or high levels of Mg2+ and the adherent cell line COLO526. In conclusion, this unique study has demonstrated for the first time the important role of the active form of LFA-1 on the lymphocyte cell surface for conjugate formation with an ICAM-1-expressing tumor cell; also, two pathways of cell signaling were identified for conjugate formation to occur.
authors.affiliation: Division of Laboratory Medicine, and the Austin Research Institute, Austin & Repatriation Medical Center, Melbourne, Australia. neeson@austin.unimelb.edu.au
authors.forename: P J
authors.initials: PJ
authors.lastname: Neeson
authors.forename: P J
authors.initials: PJ
authors.lastname: Thurlow
authors.forename: G P
authors.initials: GP
authors.lastname: Jamieson
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis; D018968:CD58 Antigens / Q000096:biosynthesis; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D019073:HT29 Cells; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D020014:K562 Cells; D008213:Lymphocyte Activation / Q000276:immunology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000096:biosynthesis; D051379:Mice; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D018968:CD58 Antigens; D015815:Cell Adhesion Molecules; C065289:ICAM2 protein, human; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1