Clonal expansions of Vδ1+ and Vδ2+ cells increase with age and limit the repertoire of human γδ T cells

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Abstract
We have investigated the complexity of the human γδ T cell repertoire by means of a VJ heteroduplex analysis method. cDNA obtained from peripheral blood mononuclear cells was amplified with Vδ1‐Cδ or Vδ2‐Cδ primers. The product was denatured and renatured to allow random reannealing of the strands and the heteroduplexes carrying mismatched junctional sequences were separated from the homoduplexes on polyacrylamide gels. Whenever one or more T cell clones were expanded to over 10% of the polyclonal background, discrete bands of homo‐ and heteroduplex appeared. This method was applied to the analysis of the peripheral γδ compartment from healthy donors and rheumatoid arthritis patients of different ages. While samples from young individuals showed a polyclonal pattern, a clear tendency towards oligoclonality appeared with increasing age, both in normal individuals and rheumatoid arthritis patients. We also show that the VJ junctional sequence derived from the heteroduplex fragments can be successfully used to isolate and characterize the corresponding T cell clones in vitro, even after a period of 1 year. In conclusion, our findings indicate that the complexity of the γδ T cell repertoire decreases with age as a consequence of the expansion of a few T cell clones.