title: Phosphatase inhibitors promote ICAM-1 and LFA-1 mediated homotypic aggregation of Jurkat and U937 cells.
abstract: Here we investigated the role of cellular phosphatases in activation of homotypic aggregation in leukocytes by adding the phosphatase inhibitors okadaic acid (OA) and calyculin A (CA) to cultures of the human monocytic U937 cell line and the human T-lymphocytic Jurkat cell line. We found that OA produces a 120-fold increase of homotypic aggregation with Jurkat cells and a 200-fold increase with U937 cells. Calyculin A increased aggregation of Jurkat cells 10-fold and U937 cells 88-fold. Monoclonal antibodies to LFA-1 completely inhibited the OA and CA induced aggregation in both cell lines, whereas the monoclonal antibody to ICAM-1 only inhibited U937 cell aggregation. These data suggest that phosphatase activity is important in the regulation of ICAM-1 and LFA-1 mediated homotypic aggregation in leukocytes.
authors.affiliation: University of Pennsylvania, Department of Medicine, Philadelphia 19104, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Weeks
authors.forename: J
authors.initials: J
authors.lastname: Iuorno
mesh_terms: D002449:Cell Aggregation / Q000502:physiology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004988:Ethers, Cyclic / Q000494:pharmacology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000502:physiology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000502:physiology*; D008387:Marine Toxins; D019319:Okadaic Acid; D010080:Oxazoles / Q000494:pharmacology*; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D004988:Ethers, Cyclic; D016169:Lymphocyte Function-Associated Antigen-1; D008387:Marine Toxins; D010080:Oxazoles; D018799:Intercellular Adhesion Molecule-1; D019319:Okadaic Acid; C059041:calyculin A; D010744:Phosphoric Monoester Hydrolases