title: Reduced phagocytosis of colloidal carriers using soluble CD47.
abstract: OBJECTIVE
  This study was designed to illustrate the feasibility of using soluble CD47 protein to antagonize phagocytosis of colloidal drug carriers by macrophages.
  
  
  METHODS
  Expression of CD47-streptavidin (CD47-SA) fusion protein was achieved in B21CodonPlus host cells following IPTG induction. Murine macrophage cell line J774A.1, expressing high levels of SIRPalpha, was selected as the biologic model system for phagocytosis. FITC-labeled perfluorocarbon (PFC) emulsions were used as the colloidal carriers to trigger phagocytosis. Microscopy (inverted light and UV-fluorescence) and flow cytometry were used to qualitatively and quantitatively determine the degree of phagocytosis, respectively.
  
  
  RESULTS
  The bacterially expressed, purified CD47-SA had neither cytotoxic nor cytostatic effects when incubated with J774A.1 cells up to a concentration of 400 nM for 24 h. Phagocytosis of FITC-labeled PFC emulsions was significantly diminished when macrophages were pretreated with 100 nM CD47-SA for 1 h.
  
  
  CONCLUSIONS
  We demonstrated that soluble CD47-SA antagonized phagocytosis of colloidal carriers to a significant degree by interaction with macrophage SIRPalpha.
authors: Department of Chemical Engineering, University of Southern California, Los Angeles, California 90089, USA.
authors: Yu-Chih
authors: YC
authors: Hsu
authors: Marcela
authors: M
authors: Acuña
authors: Stanley M
authors: SM
authors: Tahara
authors: Ching-An
authors: CA
authors: Peng
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000494:pharmacology* / Q000633:toxicity; D000943:Antigens, Differentiation / Q000378:metabolism; D051928:CD47 Antigen; D002352:Carrier Proteins / Q000235:genetics / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D003102:Colloids; D004337:Drug Carriers / Q000378:metabolism*; D004655:Emulsions; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D005466:Fluorocarbons / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects*; D017510:Protein Folding; D011971:Receptors, Immunologic / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology / Q000633:toxicity; D012995:Solubility; D019809:Streptavidin / Q000235:genetics
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D051928:CD47 Antigen; C497894:CD47 protein, human; D002352:Carrier Proteins; C497895:Cd47 protein, mouse; D003102:Colloids; D004337:Drug Carriers; D004655:Emulsions; D005456:Fluorescent Dyes; D005466:Fluorocarbons; D008562:Membrane Glycoproteins; D039842:Neural Cell Adhesion Molecule L1; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; D019809:Streptavidin; D016650:Fluorescein-5-isothiocyanate