Towards a surrogate system to express human lipid binding TCRs.

Background: Previously we reported that natural nut lipids were necessary for sensitization and that natural killer T cells (NKTs) must play a critical role in the development of food allergic responses. A major bottleneck in further understanding the interaction of nut lipids with the cells of the human immune system is the lack of well-characterized lipid responsive human cell lines.

Objective: In the present study, we engineered human T cell receptor (TCR) sequences TRAV10 and TRBV25 responsive to α-GalCer into a stable murine iNKT hybridoma and surrogate human T cell lines.

Results: The murine hybridoma system has shown to be problematic. To overcome this limitation, the expression of human TCR α/β sequences has been achieved driven by a bidirectional promoter on a plasmids or a lentivirus system, employing stable DC cell lines as lipid presenting cells, and a stable T cell line as a surrogate system. Further, a commercial human Jurkat T cell line containing an inducible secreted luciferase reporter construct was shown to be functional and can be used for a transient expression of human TCRs in a lipid screening program. The transfection efficiencies were improved using the lentivirus polycistronic constructs containing the P2A sequence in a TCR αβ/γδ null cell line (Jurkat 76).

Conclusions: The results suggest that the mis-pairing of the endogenous α/β TCR during ER folding in the presence of the new human TCR sequences could be impairing the functionality of the TCR lipid receptors. The surrogate systems presented here are important first steps in the establishment of human cell-specific lipid responsive libraries for the study of natural lipid substances.