title: Prophylactic anti-D preparations display variable decreases in Fc-fucosylation of anti-D.
abstract: BACKGROUND
  RhIG is obtained from hyperimmunized healthy anti-D donors (HIDs) boosted with D+ red blood cells (RBCs). One hypothesis for its mechanism of action is fast clearance of opsonized D+ RBCs through Fcγ receptor (FcγR)III. Levels of immunoglobulin (Ig)G Fc-fucosylation influence interactions with FcγRIII, with less Fc-fucosylation strengthening the interaction.
  
  
  METHODS
  Anti-D IgG1 Fc-glycosylation patterns in 93 plasma samples from 28 male and 28 female Dutch HIDs and RhIG were analyzed with mass spectrometry. The Fc-glycosylation profiles of HIDs were evaluated with regard to their immunization history.
  
  
  RESULTS
  HID sera demonstrated clearly lowered anti-D Fc-fucosylation compared to normal IgG fucosylation (93%); this was more pronounced for female than for male HIDs (47% vs. 65%, p = 0.001). RhIG preparations from seven manufacturers varied greatly in the level of Fc-fucosylation (56%-91%). The level of fucosylation slightly increased upon repeated immunization, although it remained fairly constant over time. The RhIG from the different manufacturers all demonstrated increased Fc-galactosylation (64%-82%) compared to total IgG (38%-51%).
  
  
  CONCLUSIONS
  RhIG preparations vary in Fc-fucosylation and all demonstrate increased galactosylation. Despite not knowing the exact working mechanism, immunoprophylaxis could perhaps be optimized by selection of donors whose anti-D have low amounts of Fc-fucose, to increase the clearance activity of anti-D preparations, as well as high amounts of galactosylation, for anti-inflammatory effects. Implementing a biologic assay in the standardization of RhIG preparations might be considered.
authors.affiliation: Department of Experimental Immunohematology, Sanquin Research, Amsterdam, The Netherlands; Landsteiner Laboratory, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Rick
authors.initials: R
authors.lastname: Kapur
authors.forename: Luciana
authors.initials: L
authors.lastname: Della Valle
authors.forename: Onno J H M
authors.initials: OJ
authors.lastname: Verhagen
authors.forename: Agnes
authors.initials: A
authors.lastname: Hipgrave Ederveen
authors.forename: Peter
authors.initials: P
authors.lastname: Ligthart
authors.forename: Masja
authors.initials: M
authors.lastname: de Haas
authors.forename: Belinda
authors.initials: B
authors.lastname: Kumpel
authors.forename: Manfred
authors.initials: M
authors.lastname: Wuhrer
authors.forename: C Ellen
authors.initials: CE
authors.lastname: van der Schoot
authors.forename: Gestur
authors.initials: G
authors.lastname: Vidarsson
mesh_terms: D000328:Adult; D001782:Blood Donors; D005260:Female; D005643:Fucose / Q000097:blood*; D005690:Galactose / Q000097:blood; D006031:Glycosylation; D006801:Humans; D007114:Immunization; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry; D007074:Immunoglobulin G / Q000737:chemistry* / Q000302:isolation & purification; D007518:Isoantibodies / Q000737:chemistry* / Q000302:isolation & purification; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011499:Protein Processing, Post-Translational; D017452:Receptors, IgG / Q000378:metabolism; D012203:Rh Isoimmunization / Q000628:therapy; D018029:Rho(D) Immune Globulin; D012727:Sex Characteristics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: C496124:FCGR3A protein, human; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007518:Isoantibodies; C061961:RHO(D) antibody; D017452:Receptors, IgG; D018029:Rho(D) Immune Globulin; D005643:Fucose; D005690:Galactose