title: Studies on the mechanism of activation of human natural killer function by interferon and inhibitors of thymidylate synthesis.
abstract: Previous publications from this laboratory have demonstrated that agents such as methotrexate (MTX), 5-fluorodeoxyuridine (FUdR), trimethoprim, and D-glucosamine (D-GlcN), which are known to inhibit thymidylate synthesis, can augment human NK activity in vitro. Furthermore, this augmentation was inhibited by exogenous thymidine (TdR) at concentrations of 10(-6) to 10(-7) M. In this report, underlying mechanisms of action of FUdR, D-GlcN, and IFN are compared. Each of these agents increased the lytic activity of effector cells bound to targets but did not increase the percentage of conjugates formed. The augmentation could be induced in a population highly enriched for NK cells (Leu-1 lb positive in phenotype). FUdR and D-GlcN could not induce any augmentation in a Leu-1 lb-negative subpopulation whereas IFN could induce significant lytic activity. alpha-Amanitin, an inhibitor of RNA polymerase II, blocked the activation of NK activity by all three reagents; hence gene expression was required. Comparison of [35S]methionine-labeled proteins by two-dimensional gel electrophoresis revealed that six new proteins were induced in IFN-treated cells. Three of these were similar in pI and molecular weight to the newly synthesized proteins in the D-GlcN-treated cells. One protein was synthesized in increased amounts in the FuDR-treated cells and it was not common to either of the other treatments. Evidence to date is consistent with the hypothesis that separate mechanisms underlie the activation of NK cells by IFN and thymidylate synthesis inhibitors, although the existence of a final common pathway for all NK response modulators cannot be excluded at the present time.
mesh_terms: D000911:Antibodies, Monoclonal; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D005467:Floxuridine / Q000494:pharmacology; D005944:Glucosamine / Q000494:pharmacology; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects*; D066298:In Vitro Techniques; D007372:Interferons / Q000494:pharmacology*; D007526:Isoelectric Point; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008970:Molecular Weight; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors*; D014158:Transcription, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D005467:Floxuridine; D012313:RNA; D007372:Interferons; D013940:Thymidylate Synthase; D005944:Glucosamine