Human eosinophils express, relative to other circulating leukocytes, large amounts of secretory 14-kD phospholipase A2

Blom, M.Lund University,Lunds universitet,Medicin, Lund,Sektion II,Institutionen för kliniska vetenskaper, Lund,Medicinska fakulteten,Medicine, Lund,Section II,Department of Clinical Sciences, Lund,Faculty of Medicine (author)

Human eosinophils perform several functions dependent on phospholipase A2 (PLA2) activity, most notably the synthesis of platelet-activating factor (PAF) and leukotriene C4 (LTC4). Several forms of PLA2 have been identified in mammalian cells. In the present study, the 14-kD, secretory form of PLA2 was detected in human eosinophils by immunocytochemical staining with the specific monoclonal antibody (MoAb) 4A1. In contrast, preparations of neutrophils, monocytes, lymphocytes, and basophils did not show detectable staining. With two MoAbs in a sandwich enzyme-linked immunosorbent assay (ELISA), large amounts of sPLA2 were detected in lysates of eosinophils, that were 20-fold to 100-fold higher than in the other circulating leukocytes (ie, neutrophils, basophils, monocytes, and lymphocytes). In addition, with a commercially available sPLA2 activity assay kit, we were able to show high activity of sPLA2 in human eosinophils relative to neutrophils. Investigations at the ultrastructural level showed that sPLA2 in eosinophils is mainly located in specific granules. Immunoelectron microscopy also visualized sPLA2 within phagosomes after addition of opsonized particles to the eosinophils. However, sPLA2 was not detected in the cell-free supernatants of activated eosinophils, in contrast to eosinophil-cationic protein (ECP), which colocalizes with sPLA2 in resting eosinophils. These findings warrant further studies into the role of sPLA2 in eosinophil function.

Tool, A. T J (author)
Wever, P. C. (author)
Wolbink, G. J. (author)
Brouwer, M. C.Lund University,Lunds universitet,Stamcellslaboratoriet för sjukdomsmodellering i det centrala nervsystemet,Forskargrupper vid Lunds universitet,IPSC Laboratory for CNS Disease Modeling,Lund University Research Groups(Swepub:lu)med-mbw (author)
Calafat, J. (author)
Egesten, A.Lund University,Lunds universitet,Lungmedicin, allergologi och palliativ medicin,Sektion II,Institutionen för kliniska vetenskaper, Lund,Medicinska fakulteten,Respiratory Medicine, Allergology, and Palliative Medicine,Section II,Department of Clinical Sciences, Lund,Faculty of Medicine(Swepub:lu)mikr-aeg (author)
Knol, E. F. (author)
Hack, C. E. (author)
Roos, D. (author)
Verhoeven, A. J.Sanquin Blood Supply (author)
Medicin, LundSektion II (creator_code:org_t)

By the author/editor: Blom, M.; Tool, A. T J; Wever, P. C.; Wolbink, G. J.; Brouwer, M. C.; Calafat, J.; show more...; Egesten, A.; Knol, E. F.; Hack, C. E.; Roos, D.; Verhoeven, A. J.; show less...

About the subject

MEDICAL AND HEALTH SCIENCES: MEDICAL AND HEAL ...; and Clinical Medicin ...; and Hematology

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