Rapid and strong induction of apoptosis in human eosinophils by anti-CD30 mAb-coated microspheres and phagocytosis by macrophages.
BACKGROUND
Eosinophils represent a potential therapeutic target in allergic diseases. We previously reported that two clones of anti-CD30 mAbs (HRS-4 and Ber-H8) induced extremely rapid and intense apoptosis in human eosinophils in vitro, but only when the mAbs were immobilized on plates [Matsumoto K, J Immunol 2004;172:2186]. As the initial step towards clinical application of these anti-CD30 mAbs in the treatment of allergic diseases, we made an attempt to clarify two issues; first, whether or not anti-CD30 mAb-coated microspheres can efficiently induce apoptosis in human eosinophils, and second, whether or not these apoptotic eosinophils can be phagocytosed by macrophages without the release of granular proteins.


METHODS
Purified human eosinophils were treated with anti-CD30 mAb-coated polystyrene microspheres (diameter, 1.44 mum). Apoptosis was determined by annexin V-binding. For the phagocytosis assay, eosinophils were co-cultured with monocyte-derived human macrophages or PMA-pretreated U-937 cells. Phagocytosis was determined by light microscopy and by the eosinophil-derived neurotoxin (EDN) concentration in the supernatant.


RESULTS
Anti-CD30 mAb-coated, but not control IgG1-coated microspheres significantly reduced eosinophil survival in a dose-dependent manner. Marked phagocytosis of the apoptotic eosinophils by macrophages was also observed when the eosinophils were treated with anti-CD30 mAb-coated microspheres. The apoptotic eosinophils released large amounts of EDN in the absence of macrophages; however, the EDN levels were significantly decreased when the eosinophils were co-cultured with macrophages.


CONCLUSIONS
Anti-CD30 mAb-coated microspheres are capable of inducing rapid and strong apoptosis in human eosinophils. Furthermore, the apoptotic eosinophils were also phagocytosed by macrophages with minimal release of the granular proteins.
Matsumoto
Kenji
K
Department of Allergy and Immunology, National Research Institute for Child Health and Development, Tokyo, Japan. kmatsumoto@nch.go.jp
Terakawa
Maki
M
Fukuda
Shuhei
S
Saito
Hirohisa
H
D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D017209:Apoptosis / Q000276:immunology*; D002478:Cells, Cultured / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018920:Coculture Techniques; D004306:Dose-Response Relationship, Immunologic; D047208:Eosinophil-Derived Neurotoxin / Q000378:metabolism; D004804:Eosinophils / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D017730:Ki-1 Antigen / Q000037:antagonists & inhibitors* / Q000276:immunology; D008264:Macrophages / Q000276:immunology*; D008863:Microspheres; D010587:Phagocytosis / Q000276:immunology*; D011137:Polystyrenes; D012130:Respiratory Hypersensitivity / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D020298:U937 Cells / Q000187:drug effects
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D017730:Ki-1 Antigen; D011137:Polystyrenes; D047208:Eosinophil-Derived Neurotoxin; D013755:Tetradecanoylphorbol Acetate