Phorbol ester-induced degranulation in adherent human eosinophil granulocytes is dependent on CD11/CD18 leukocyte integrins.
Secretion of unique eosinophil granule constituents may play a role in allergic and parasitic reactions. Therefore we have investigated possible mechanisms for regulation of secretion in eosinophils. A hemolytic plaque assay and an enzyme-linked immunospot (ELISPOT) assay were developed for detection of secreted eosinophil cationic protein (ECP) from single adherent eosinophils. The protein kinase C activator phorbol 12-myristate 13-acetate (PMA) induced release of ECP in a dose-dependent fashion but 4-alpha-PMA, an analogue that does not activate protein kinase C, did not cause degranulation. Staurosporine and K252a, inhibitors of protein kinase C, decreased PMA-induced ECP secretion. Low concentrations of cytochalasin B enhanced PMA-induced secretion but high concentrations had an inhibitory effect. The calcium ionophores A23187 and ionomycin were weaker secretagogues than PMA. Tumor necrosis factor, granulocyte-macrophage colony-stimulating factor, interleukin-3, interleukin-5, N-formylmethionyl-leucyl-phenylalanine, and lipopolysaccharide caused little or no degranulation in adherent eosinophils. Preincubation of eosinophils with antibodies to CD18, the common beta chain of leukocyte adhesion proteins, resulted in inhibition of PMA-induced ECP release from adherent cells. 1,2-Bis(O-aminophenyl)-ethane-ethane-N,N,N',N'-tetraacetic acid (BAPTA), an agent that acts intracellularly by chelation of calcium, also inhibited PMA-mediated ECP release. In conclusion, PMA induces release of ECP from single adherent eosinophils and the effect appears to be mediated via protein kinase C and, in contrast to that in neutrophils, to be dependent on CD11/CD18 leukocyte integrins.
Egesten
A
A
Department of Medicine, University of Lund, Sweden.
Gullberg
U
U
Olsson
I
I
Richter
J
J
D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology / Q000494:pharmacology; D001798:Blood Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D018845:CD11 Antigens; D018821:CD18 Antigens; D000001:Calcimycin / Q000494:pharmacology; D002448:Cell Adhesion; D015550:Cell Degranulation / Q000187:drug effects*; D002614:Chelating Agents / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000166:cytology / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D016023:Integrins / Q000187:drug effects; D007377:Interleukin-3 / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012260:Ribonucleases; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000906:Antibodies; D015703:Antigens, CD; D001798:Blood Proteins; D018845:CD11 Antigens; D018821:CD18 Antigens; D002614:Chelating Agents; D047091:Eosinophil Granule Proteins; D016023:Integrins; D007377:Interleukin-3; D008070:Lipopolysaccharides; D010703:Phorbol Esters; D014409:Tumor Necrosis Factor-alpha; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D000001:Calcimycin; D003571:Cytochalasin B; D004533:Egtazic Acid; D015759:Ionomycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011493:Protein Kinase C; D012260:Ribonucleases; D013755:Tetradecanoylphorbol Acetate