title: Localization of Fc and Fab fragments of nonspecific polyclonal IgG at focal sites of inflammation.
abstract: Intact IgG, Fc, Fab, and 1/2Fc (reduced and alkylated Fc) were coupled to DTPA, labeled with indium-111 and administered to rats to compare the ability of fragments of IgG to localize at focal sites of inflammation. Two sets of experiments were performed: First, 1, 6, 24, and 48 hr after injection, biodistribution was determined in healthy animals; second, localization at sites of inflammation was determined by scintillation camera imaging of animals with deep-thigh infection due to Escherichia coli. The biodistribution studies demonstrated differences in kidney and liver localization: IgG less than Fc less than Fab less than 1/2Fc (kidney), Fc less than 1/2Fc less than IgG less than Fab (liver). The imaging studies revealed that target-to-background ratio (T/B) and percent residual activity (%RA) for IgG was significantly greater (p less than 0.01) than 1/2 Fc or Fab, and T/B for IgG was greater (p less than 0.01) than Fc. These studies suggest that the Fc portion of IgG is the fragment with the best imaging properties.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston 02114.
authors.forename: A J
authors.initials: AJ
authors.lastname: Fischman
authors.forename: R H
authors.initials: RH
authors.lastname: Rubin
authors.forename: J A
authors.initials: JA
authors.lastname: White
authors.forename: E
authors.initials: E
authors.lastname: Locke
authors.forename: R A
authors.initials: RA
authors.lastname: Wilkinson
authors.forename: M
authors.initials: M
authors.lastname: Nedelman
authors.forename: R J
authors.initials: RJ
authors.lastname: Callahan
authors.forename: B A
authors.initials: BA
authors.lastname: Khaw
authors.forename: H W
authors.initials: HW
authors.lastname: Strauss
mesh_terms: D000818:Animals; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007205:Indium Radioisotopes; D007249:Inflammation / Q000000981:diagnostic imaging* / Q000276:immunology; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D011877:Radionuclide Imaging; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000000981:diagnostic imaging
chemical_list: D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007205:Indium Radioisotopes