Determining the histocompatibility barriers between universal CAR T cells (UCART) and NK cellsKimberly Apodaca Gerald P. Linette Allogeneic chimeric antigen receptor (CAR) T cell therapies hold promise for certain malignant disorders as they allow for scalability, on-demand availability, and enhanced product quality. Currently, allogeneic CAR T cell approaches focus on deleting the αβTCR complex and MHC-I/II from CAR T cells to prevent GvHD and rejection of allogeneic cells by the recipient’s immune system. However, genetic ablation of MHC-I leads to NK cell activation in recipients due to the “missing-self” response. In this thesis, we demonstrate the successful generation of universal CART (UCART) cells that evade the NK cell “missing-self” response and display similar performance to autologous CAR T cells both in vitro and in vivo. An HLA single-chain trimer (ScT) platform enabled our demonstration that HLA-E presentation of a defined signal peptide sequence, VMAPRTLIL (designated as HLA-ESP-1C), confers resistance to NKG2A+ cell populations with negligible activation of NKG2C+ cell populations. Examination of additional receptor-ligand interactions that may impact NK cell activation confirmed that CD54 and CD58 ablation on UCART cells, in combination with HLA-ESP-1C expression, led to optimal resistance to heterogenous NKG2A+/C+ NK cell populations. Finally, in a humanized mouse model reconstituted with allogeneic NK cells, we demonstrate that UCART19 cells promote stringent tumor control. This work suggests an updated approach for allogeneic CART cell therapy for clinical applications.