The Expression of LDL-R in CD8⁺ T Cells Serves as an Early Assessment Parameter for the Production of TCR-T Cells

The quantity and the phenotypes of desired T cell receptor engineered T (TCR-T) cells in the final cell product determine their in vivo anti-tumor efficacy. Optimization of key steps in the TCR-T cell production process, such as T cell activation, has been shown to improve cell quality.

Using a modified TCR (mTCR) derived from mice transducing PBMCs, we assessed the proportions of low-density lipoprotein receptor (LDL-R) and mTCR expressing cells under the various activation conditions of CD3/CD28-Dynabeads or OKT3 via flow cytometry.

We demonstrate that the proportion of T cells expressing LDL-R post activation is positively correlated with the percentage of mTCR⁺CD8⁺ T cells with their less differentiated subtypes in the final product. In addition, we show that shifting the CD3/CD28-Dynabeads activation duration from a typical 48 h to 24 h can significantly increase the production of the desired mTCR⁺CD8⁺ T cells. Importantly, the percentages of TCR-T cells with less-differentiated phenotypes, namely mTCR central memory T cells (T_CM), were found to be preserved with markedly higher efficiency when T cell activation was optimized.

Our findings suggest that the proportion of LDL-R⁺ T cells may serve as an early assessment parameter for evaluating TCR-T cell quality, possibly facilitating the functional and economical improvement of current adoptive therapy.