Dissecting the crosstalk between inhibitory receptor signaling and the T cell receptor in natural killer cells

Abstract

Killer-cell immunoglobulin-like receptors (KIRs) are among the most prominent receptors regulating NK cell development and function. Most KIR ligands are the MHC class I molecules found on target cells. KIRs are responsible for NK cell licensing which is required for the NK cell to kill and differentiate self from non-self. Adoptive cell therapy based on T cell transfer relies on T cell receptor (TCR) or chimeric antigen receptor (CAR). However, with the TCR-T cells, the most important challenge is mispairing of transferred TCR chains with the endogenous TCR chains. Recently, TCR modification of NK cells has been applied as a solution to the mispairing of TCR chains in T cells. NK cells, with their similar downstream signaling machinery to T cells, can replace T cells in TCR-T cell therapy. These modifications were performed on NK92 cells that lacks inhibitors. This study tries to elucidate how inhibitory signals interfere with TCR signaling. TCR-NK cells against the melanoma-associated antigen Tyrosinase, have been transduced with KIR2DL1 coding lentiviral particles for stable KIR2DL1 expression. The function of the TCR-NK-KIR2DL1 cells was measured against K562 or melanoma cells A375 and A375Tyr. The degranulation of TCR-NK-KIR2DL1 cells was observed to be slightly higher independent from the antigen. Similarly, real- time cell analysis showed the cytotoxicity induced by KIR2DL1 did not show a significant difference. Cy tokine secretion showed there might be a KIR2DL1-mediated TNF-α decrease against A375Tyr cells, but not the same for IFN-γ secretion. Phospho- protein analysis of TCR-NK-KIR2DL1 showed a decrease in PLCγ1 and Erk1/2 levels against all targets.