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Phorbol ester‐induced degranulation in adherent human eosinophil granulocytes is dependent on CD11/CD18 leukocyte integrins
Author(s) -
Egesten Arne,
Gullberg Urban,
Olsson Inge,
Richter Johan
Publication year - 1993
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.53.3.287
Subject(s) - degranulation , ionomycin , eosinophil cationic protein , protein kinase c , cytochalasin b , microbiology and biotechnology , eosinophil peroxidase , biology , secretion , granulocyte , phorbol , eosinophil , cd18 , biochemistry , immunology , kinase , flow cytometry , in vitro , integrin alpha m , receptor , asthma
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 immu‐nospot (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‐αPMA, an analogue that does not activate protein kinase C, did not cause degranulation. Staurosporin 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‐formylmeth‐ionyl‐leucyl‐phenylalanine, and lipopolysaccharide caused little or no degranulation in adherent eosinophils. Preincubation of eosinophils with antibodies to CD18, the common β chain of leukocyte adhesion proteins, resulted in inhibition of PMA‐induced ECP release from adherent cells. l,2‐Bis(O‐aminophenyl)ethane‐ethane‐N,N,N,N′‐tet‐raacetic 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.