Specific selection of stimulation-responsive γδ T-cells utilizing a short-term activation assay.

Abstract

T cells expressing the γδ T-cell receptor (TCR) represent a numerically small proportion of total T cells. Unlike αβ T cells they are activated by non-peptide antigens independently of MHC-presentation. γδ T cells have been recognized as a favorable prognostic marker across different tumor entities. Recently, γδ T cells (in particular Vδ2 T cells), have gained attention because of their effective intrinsic anti-tumor reactivity. Moreover, their ability for MHC-independent activation and in vitro expansion to high numbers makes them attractive candidates for tumor immunotherapy by adoptive transfer. In this regard, the ex vitro identification of highly reactive γδ T cells upon stimulation enables us to specifically identify, isolate and expand γδ T cells which potentially represent those with high anti-tumor reactivity. CD137 and CD154 represent suitable markers for identifying specifically activated γδ T cells. In humans, the surface mobilization of CD137 and CD154 reveals antigen-specific activation of regulatory (Treg) and conventional CD4 T cells, respectively. We adapted this method for the analysis of Vδ2 T cells, in which the mobilization of both CD137 and CD154 can be used to investigate their activation, whereby CD137 and CD154 do not discriminate regulatory from conventional cells. Thus, this method provides a new way to rapidly analyze quick changes in Vδ2 T-cell activation and allows for using these markers for cell sorting and subsequent expansion of the specifically reacting Vδ2 T cells.