Studies of a murine monoclonal antibody directed against DARC: reappraisal of its specificity

PLoS One. 2015 Feb 23;10(2):e0116472. doi: 10.1371/journal.pone.0116472. eCollection 2015.

Abstract

Duffy Antigen Receptor for Chemokines (DARC) plays multiple roles in human health as a blood group antigen, a receptor for chemokines and the only known receptor for Plasmodium vivax merozoites. It is the target of the murine anti-Fy6 monoclonal antibody 2C3 which binds to the first extracellular domain (ECD1), but exact nature of the recognized epitope was a subject of contradictory reports. Here, using a set of complex experiments which include expression of DARC with amino acid substitutions within the Fy6 epitope in E. coli and K562 cells, ELISA, surface plasmon resonance (SPR) and flow cytometry, we have resolved discrepancies between previously published reports and show that the basic epitope recognized by 2C3 antibody is 22FEDVW26, with 22F and 26W being the most important residues. In addition, we demonstrated that 30Y plays an auxiliary role in binding, particularly when the residue is sulfated. The STD-NMR studies performed using 2C3-derived Fab and synthetic peptide corroborated most of these results, and together with the molecular modelling suggested that 25V is not involved in direct interactions with the antibody, but determines folding of the epitope backbone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal*
  • Antibody Specificity
  • Binding Sites, Antibody
  • Duffy Blood-Group System / immunology*
  • Epitopes / immunology*
  • Escherichia coli / metabolism
  • Humans
  • Mice
  • Receptors, Cell Surface / immunology*

Substances

  • ACKR1 protein, human
  • Antibodies, Monoclonal
  • Duffy Blood-Group System
  • Epitopes
  • Receptors, Cell Surface

Grants and funding

This work was supported by a grant from National Science Centre in Poland (Grant No. N N 401 536640). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.