Glomerular T Cells Are of Restricted Clonality and Express Multiple CDR3 Motifs across Different Vβ T-Cell Receptor Families in Experimental Autoimmune Glomerulonephritis

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Abstract
Experimental autoimmune glomerulonephritis (EAG) is an animal model of Goodpasture’s disease which can be induced in Wistar-Kyoto (WKY) rats by a single intramuscular injection of collagenase-digested rat glomerular basement membrane (GBM) in adjuvant. This model is characterised by anti-GBM antibody production, accompanied by focal necrotising glomerulonephritis with crescent formation and glomerular infiltration by T cells and macrophages. Previous work has shown that EAG is a T-cell-dependent disease. We proposed that intraglomerular T cells might be directly involved in pathogenesis and would be oligoclonal. In this study, EAG was induced by standard methods, the kidneys perfused with saline at week 2 and week 4, and the glomeruli separated by a sieving method. Glomerular RNA was extracted and reverse transcribed. RT-PCR showed overexpression of an average of two Vβ families in each kidney analysed. However, no predominant single Vβ family was overexpressed in any of the experimental animals. CDR3 spectratyping of Fam-labelled PCR products showed a marked restriction involving different Vβ families. Sequencing demonstrated multiple CDR3 motifs, each expressed in association with different Vβ gene segments. Our results show that glomerular T cells are of restricted clonality and suggest a role for antigen-specific effector T cells in the pathogenesis of EAG.