Single-cell TCR analysis of mouse lung Vγ4 γδ T cells reveals a link between TCR clonotypes, SLAM family receptor expression, and effector function

Abstract

γδ T cells are unusual T cells that are highly enriched in mucosal tissues where they constitute a prominent source of pro-inflammatory cytokines like IL-17 and IFN-γ. The TCR usage of tissue-specific γδ T cells is often associated with specific effector functions. We have recently found that IL-17- and IFN-γ-producing Vγ4 γδ T cells in the mouse lung are marked by the expression of SLAMF1 and SLAMF6 receptors, respectively. The objective of this study was to investigate a possible link between SLAM-associated effector function and γδ TCR usage. We first identified the major Vγ4 γδ TCR clonotypes in the mouse lung (n=13 mice). Vγ4 γδ T cells were single cell-sorted and paired TCR clonotypes were identified using next-gen sequencing of TCR amplicon libraries. The data revealed that TRDV5, TRDV2, and TRDV7 chains accounted for 51.18%, 29.61%, and 14.96% of the productive TCRδ chain rearrangements, respectively. While TRDV5 and TRDV2 CDR3 sequences were limited in diversity, TRDV7 CDR3 sequences were highly diverse. A significant fraction (30.46%) of the TRDV5 sequences were characterized by an invariant germline-encoded Vδ5Dδ2Jδ1 sequence. A comparison between sorted SLAMF1+ and SLAMF6+lung Vγ4 γδ T cells revealed that TRDV5 and TRDV2 chains were predominantly associated with SLAMF1+IL-17+ γδ T cells while the TRDV7 chain was predominantly associated with SLAMF6+IFN-γ+ γδ T cells. Moreover, the invariant germline-encoded TRDV5 sequence was primarily associated with SLAMF1+IL-17+ cells. These data indicate that the lung Vγ4 γδ TCR repertoire is limited in diversity and that specific lung Vγ4 γδ TCR clonotypes segregate with the expression of discrete SLAM family receptors.