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T cell receptor BV gene usage in interstitial cellular infiltrates in active Heymann nephritis
1Centre for Kidney Research, Royal Alexandra Hospital for Children, Westmead, New South Wales, Australia.
Background:
Infiltration of the kidney by mononuclear cells is a prominent feature of active Heymann nephritis (HN). These cells could be present as a part of generalized inflammatory response, or could be proliferating in response to specific antigens. To examine these questions, we have analysed the T cell receptor (TCR) BV repertoire of T cells infiltrating the renal interstitium at regular time intervals throughout the course of the disease.
Methods:
HN was induced in Lewis rats by immunization with renal tubular antigen (Fx1A) in complete Freund's adjuvant (CFA). Kidneys were collected 8 and 12 weeks after immunization. Renal tissue was homogenized and RNA extracted. RT-PCR and sequencing were used to characterize expression of TCR BV genes.
Results:
Preferential expression of TCR BV2 and BV16 gene families was seen at 8 weeks. By 12 weeks the diversity of the TCR BV gene repertoire had increased and was highly heterogeneous. Sequence analysis of BV2, and BV16 RT-PCR products from 8 week HN kidneys revealed conserved usage of CDR3 regions, and an over-representation of arginine residues in the CDR3 regions at a frequency of between 60 and 100% of clones sequenced in most of BV2 and BV16 subfamilies.
Conclusion:
The preferential usage of CDR3 region sequences in TCR BV2 and BV 16 families indicates clonal expansion of individual T cells in HN kidneys at 8 weeks. The conserved usage of arginine residues in the CDR3 regions may indicate recognition of select antigenic epitopes. By 12 weeks, the diverse TCR BV repertoire in the kidney may be due to epitope spreading or may represent a non-specific inflammatory response in the late phase of the disease.