title: Glycosyl-phosphatidyl-inositol-defective granulocytes from paroxysmal nocturnal haemoglobinuria patients show increased bacterial ingestion but reduced respiratory burst induction.
abstract: Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by the emergence of a GPI-defective clonal hematopoiesis. Its clinical features are hemolytic anemia, cytopenia, and thrombosis. Circulating monocytes and granulocytes are largely GPI-defective in PNH patients. This study aims to investigate the granulocyte functional properties in PNH. We analyzed bacterial-dependent intracellular ingestion and the consequent activation of oxidative burst in GPI-defective granulocytes from four neutropenic PNH patients. Our data show a significant increase in the ability of GPI-defective granulocytes to ingest opsonized bacteria. In addition, an impaired respiratory burst effectiveness in response to two independent bacterial stimuli, the N-formyl-MetLeuPhe (fMLP) synthetic bacterial peptide and E. coli, was revealed. The occurrence of neutropenia and the severe impairment of oxidative burst, occurring in chronic granulomatosis disease, were unable to significantly affect phagocytosis. Thus, additional mechanisms, able to differentially affect ingestion ability and respiratory burst effectiveness, have to be hypothesized. The reduced burst effectiveness of GPI-defective granulocytes was maintained after treatment with phorbol 12-myristate 13-acetate, a pharmacological stimulus able to extensively recruit and to trigger intracellular protein kinase C (PKC). Moreover, blocking of PKC has been observed to severely affect granulocyte respiratory burst with a mild effect on the phagocytosis. These data suggest a role for a modulation of intracellular PKC in the pathogenesis of the impaired granulocyte oxidative burst.
authors.affiliation: Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Naples, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Cacciapuoti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Terrazzano
authors.forename: Lucia
authors.initials: L
authors.lastname: Barone
authors.forename: Michela
authors.initials: M
authors.lastname: Sica
authors.forename: Cristina
authors.initials: C
authors.lastname: Becchimanzi
authors.forename: Bruno
authors.initials: B
authors.lastname: Rotoli
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Ruggiero
authors.forename: Fiorella
authors.initials: F
authors.lastname: Alfinito
mesh_terms: D000328:Adult; D000818:Animals; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology*; D017261:Glycosylphosphatidylinositols / Q000172:deficiency* / Q000276:immunology; D006098:Granulocytes / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D006105:Granulomatous Disease, Chronic / Q000209:etiology / Q000235:genetics / Q000276:immunology / Q000473:pathology; D006410:Hematopoiesis / Q000235:genetics / Q000276:immunology; D006457:Hemoglobinuria, Paroxysmal / Q000150:complications / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D006801:Humans; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009503:Neutropenia / Q000150:complications / Q000235:genetics / Q000276:immunology / Q000473:pathology; D010587:Phagocytosis / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D011493:Protein Kinase C / Q000276:immunology; D016897:Respiratory Burst / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D002273:Carcinogens; D017261:Glycosylphosphatidylinositols; D009240:N-Formylmethionine Leucyl-Phenylalanine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate