The structure of anti-Gal immunoglobulin genes in naïve and stimulated Gal knockout mice

Hui Xu, Ajay Shama, Libing Chen, Caren Harrison, Yuanyuan Wei, Anita S.F. Chong, John S. Logan, Guerard W. Byrne

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Background. Naturally occurring antibodies (Nabs) that bind to terminal galactose α1,3-galactose carbohydrate structures (Gal) are present in humans and Old World monkeys but are negatively regulated in other mammalian species because they express Gal epitopes on their cell surfaces. A Gal knockout mouse (Gal-/-) model, generated by homologous disruption of α1,3-galactosyltransferase gene, is capable of producing natural anti-Gal Abs. Methods. To study the genetic control of the anti-Gal response, we have generated anti-Gal hybridomas from Gal-/- mice and analyzed VH genes of anti-Gal Abs from naive animals and from mice stimulated by rat heterotopic heart transplantation. Results. Six immunoglobulin (Ig)M anti-Gal hybridomas derived from naïve Ga-/- mice exhibited anti-Gal binding activity with some cross-reactivity to related carbohydrate structures. These naïve anti-Gal Abs used five different VH genes in a germline configuration. Anti-Gal IgM hybridomas isolated after a rat heterotopic heart xenograft (4 days) utilized germline VH gene segments from the VH7183 family and exhibited less cross-reactivity. In contrast to mice 4 days after xenograft, we have predominantly isolated IgG antiGal hybridomas from mice 21 days after rat heterotopic heart xenografts, indicating an isotype switch. Nine of the IgG anti-Gal hybridomas secreted IgG3 subclass and one produced IgG1. Sequence analysis of the VH gene usage from the induced anti-Gal IgG antibodies demonstrated a restricted gene utilization (VHJ606-V14A). Conclusion. Our results demonstrate that the antiGal response in naïve Gal-/- mice is encoded by multiple germline progenitors. In response to a xenograft, the induced anti-Gal Abs exhibited a restricted gene usage and somatic mutations, indicating a positive selection.

Original languageEnglish (US)
Pages (from-to)1817-1825
Number of pages9
JournalTransplantation
Volume72
Issue number11
DOIs
StatePublished - Dec 15 2001
Externally publishedYes

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