Designing a soluble TCR as a tool for identifying phospho-antigen-presenting molecules for Vγ9Vδ2 T cells

Abstract

A complex defence system has been conserved amid various animal species. Among the T lymphocyte population, an in 1986 discovered subset carries a γδ T cell receptor (TCR) instead of the conventional αβ TCR. 2-5% of the peripheral CD3 positive cells and approximately 90% of γδ T cells, express the Vγ9Vδ2 TCR. This γδ T cell subset has been shown to recognise various small phosphorylated molecules, among them is isopentenyl pyrophosphate (IPP). IPP seems to be the ligand for the activation and stimulation of Vγ9Vδ2 T cells. However, IPP is too small to possess the degree of affinity that is required to bind to the γδ TCR. Besides, experiments have failed to prove that IPP directly binds to the TCR. Therefore, it is probable that an IPP presenting molecule is involved. Ecto-F1-ATPase and heat shock proteins make good candidates. However, more proteins may have the IPP presentation ability. We have designed a soluble TCR (scTCR) gene containing vector, suitable for scTCR production in eukaryotic cells. The synthesized scTCRs can be used for various assays aimed at identifying Vγ9Vδ2 TCR ligands, presenting molecules and mechanisms of γδ T cell activation.