Lambrianides, A.;
Giles, I.;
Ioannou, Y.;
Mason, L.;
Latchman, D.S.;
Manson, J.J.;
Isenberg, D.A.;
(2007)
Arginine mutation alters binding of a human monoclonal antibody to antigens linked to systemic lupus erythematosus and the antiphospholipid syndrome.
Arthritis and Rheumatism
, 56
(7)
pp. 2392-2401.
10.1002/art.22743.
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Abstract
Objective: Previous studies have shown the importance of somatic mutations and arginine residues in the complementarity-determining regions (CDRs) of pathogenic anti-double-stranded DNA (anti-dsDNA) antibodies in human and murine lupus, and in studies of murine antibodies, a role of mutations at position 53 in VH CDR2 has been demonstrated. We previously demonstrated in vitro expression and mutagenesis of the human IgG1 monoclonal antibody B3. The present study was undertaken to investigate, using this expression system, the importance of the arginine residue at position 53 (R53) in B3 VH. Methods: R53 was altered, by site-directed mutagenesis, to serine, asparagine, or lysine, to create 3 expressed variants of VH. In addition, the germline sequence of the VH3-23 gene (from which B3 VH is derived) was expressed either with or without arginine at position 53. These 5 new heavy chains, as well as wild-type B3 VH, were expressed with 4 different light chains, and the resulting antibodies were assessed for their ability to bind to nucleosomes, -actinin, cardiolipin, ovalbumin, 2-glycoprotein I (2GPI), and the N-terminal domain of 2GPI (domain I), using direct binding assays. Results: The presence of R53 was essential but not sufficient for binding to dsDNA and nucleosomes. Conversely, the presence of R53 reduced binding to -actinin, ovalbumin, 2GPI, and domain I of 2GPI. The combination B3 (R53S) VH/B3 VL bound human, but not bovine, 2GPI. Conclusion: The fact that the R53S substitution significantly alters binding of B3 to different clinically relevant antigens, but that the alteration is in opposite directions depending on the antigen, implies that this arginine residue plays a critical role in the affinity maturation of antibody B3.
| Type: | Article |
|---|---|
| Title: | Arginine mutation alters binding of a human monoclonal antibody to antigens linked to systemic lupus erythematosus and the antiphospholipid syndrome |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/art.22743 |
| Publisher version: | http://dx.doi.org/doi:10.1002/art.22743 |
| Language: | English |
| Additional information: | The attached paper contains Figure 2. Effect of point mutation in B3VH and VH3-23. The graphs show binding of IgG in COS-7 cell supernatants containing each heavy/light chain combination to (a) nucleosomes and (b) dsDNA. |
| UCL classification: | |
| URI: | https://discovery.ucl.ac.uk/id/eprint/2607 |
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