TCR sequences and tissue distribution discriminate the subsets of naïve and activated/memory Treg cells in mice

Anne-Sophie Bergot, Wahiba Chaara, Eliana Ruggiero, Encarnita Mariotti-Ferrandiz, Sophie Dulauroy, Manfred Schmidt, Christof von Kalle, Adrien Six, David Klatzmann

Analyses of the regulatory T (Treg) cell TCR repertoire should help elucidate the nature and diversity of their cognate antigens and thus how Treg cells protect us from autoimmune diseases. We earlier identified CD44(hi) CD62L(low) activated/memory (am) Treg cells as a Treg-cell subset with a high turnover and possible self-specificity. We now report that amTreg cells are predominantly distributed in lymph nodes (LNs) draining deep tissues. Multivariate analyses of CDR3 spectratyping first revealed that amTreg TCR repertoire is different from that of naïve Treg cells and effector T (Teff) cells. Furthermore, in deep- versus superficial-LNs, TCRβ-deep-sequencing further revealed diversified naïve Treg-cell and amTreg-cell repertoires, although 2-fold less diverse than that of Teff cells, and with repertoire richness significantly lower in deep-LN versus superficial-LNs Treg cells. Importantly, expanded clonotypes were mostly detected in deep-LN amTreg cells, some accounting for 20% of the repertoire. Strikingly, these clonotypes were absent from naïve Treg cells, but found at low frequency in Teff cells. Our results, obtained in non-manipulated mice, indicate different antigenic targets for naïve and amTreg cells and that amTreg cells are self-specific. The data we present are consistent with an instructive component in Treg-cell differentiation. This article is protected by copyright. All rights reserved.