title: Protein tyrosine kinase inhibition blocks granule exocytosis and cytolytic function of lymphokine-activated killer cells.
abstract: Short-term pretreatment of human lymphokine-activated killer cells (LAK) with the protein tyrosine kinase-specific inhibitor Herbimycin A (Herb A) blocked cytotoxic function against the NK-resistant (LAK-sensitive) tumor targets, SK-Mel-1 (human melanoma) and Daudi (human lymphoma). Greater than 50% inhibition of LAK activity was observed after a 2.5-h pretreatment with 0.125 microgram/ml (ca. 0.2 microM) Herb A. Inhibition of LAK occurred over a time interval in which LAK were not dependent upon IL-2 for maintenance of killing function, supporting the conclusion that the drug interfered with mobilization of cytotoxic function. Conjugate formation between LAK and tumor targets was unaffected by Herb A, indicating that inhibition was occurring at a post-binding step. Granule exocytosis as measured by BLT-esterase release was detected from LAK after coincubation with tumor targets, and was inhibited by Herb A pretreatment. The majority of LAK killing was dependent upon extracellular calcium, supporting the hypothesis that granule exocytosis rather than Fas ligand was the principal pathway leading to target cell death. The data suggest that protein tyrosine kinases play a pivotal role in LAK cytolytic function by regulating granule exocytosis.
authors.affiliation: Department of Tumor Biology, University of Texas 77030, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Frederick
authors.forename: T K
authors.initials: TK
authors.lastname: Yu
authors.forename: E G
authors.initials: EG
authors.lastname: Krohn
authors.forename: D A
authors.initials: DA
authors.lastname: Johnston
authors.forename: E A
authors.initials: EA
authors.lastname: Grimm
mesh_terms: D016227:Benzoquinones; D002449:Cell Aggregation / Q000187:drug effects; D003594:Cytoplasmic Granules / Q000187:drug effects*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005089:Exocytosis / Q000187:drug effects*; D053222:Fas Ligand Protein; D053804:Granzymes; D006801:Humans; D007376:Interleukin-2 / Q000037:antagonists & inhibitors; D015979:Killer Cells, Lymphokine-Activated / Q000187:drug effects*; D047029:Lactams, Macrocyclic; D008024:Ligands; D008562:Membrane Glycoproteins / Q000187:drug effects / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011809:Quinones / Q000494:pharmacology*; D017828:Rifabutin / Q000031:analogs & derivatives; D012697:Serine Endopeptidases / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D007376:Interleukin-2; D047029:Lactams, Macrocyclic; D008024:Ligands; D008562:Membrane Glycoproteins; D011809:Quinones; D017828:Rifabutin; C020754:herbimycin; D011505:Protein-Tyrosine Kinases; D053804:Granzymes; D012697:Serine Endopeptidases; C509212:GZMA protein, human