Structural and functional characterization of glycosylation in an immunoglobulin G1 to Cryptococcus neoformans glucuronoxylomannan

Fang Wang, Antonio Nakouzi, Mauricio Alvarez, Oscar Zaragoza, Ruth Hogue Angeletti, Arturo Casadevall

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Analysis of the N-linked oligosaccharides of the murine IgG1 monoclonal antibody (mAb) to Cryptococcus neoformans by LC/MS revealed five different core fucosylated, biantennary complex-type oligosaccharides at Asn-293, with the major species being a mono-galactosylated oligosaccharide with the glycosyl composition of Hex4HexNAc4Fuc (39% of the total glycan pool). The primary sequence predicted from nucleic acid sequencing differed from that measured by mass spectrometry at position 33 (ASN to ASP), a finding that may represent post-translational modification caused by spontaneous ASP deamination. Analysis of mAb 18B7 from three hybridoma clones revealed the same heterogenous N-glycan pattern, indicating that diversity in oligosaccharide structures originated from individual cells. The binding of native and de-glycosylated mAb 18B7 to cryptococcal Ag was comparable but the de-glycosylated 18B7 had shorter serum half-life and did not activate complement (C). De-glycosylated mAb 18B7 was opsonic for C. neoformans with murine macrophages through a mechanism that involved C-independent ingestion through the C receptor. Passive administration of de-glycosylated mAb 18B7 mediated comparable protective efficacy to the native mAb in mice with lethal infection. The results imply that the contribution of N-glycan structure to immunoglobulin function varies depending on the Ag-Ab system.

Original languageEnglish (US)
Pages (from-to)987-998
Number of pages12
JournalMolecular Immunology
Volume43
Issue number7
DOIs
StatePublished - Mar 1 2006

Keywords

  • Antibodies
  • Antigens
  • Fungal
  • Phagocytosis
  • Rodent

ASJC Scopus subject areas

  • Immunology
  • Molecular Biology

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