Determining if T cell antigens are naturally processed and presented on HLA class I molecules

Determining T cell responses to naturally processed and presented antigens is a critical immune correlate to determine efficacy of an investigational immunotherapeutic in clinical trials. In most cases, minimal epitopes and HLA restriction elements are unknown. Here, we detail the experimental use of ex vivo expanded autologous B cells as antigen presenting cells to overcome the limitation of unknown HLA restriction, and the use of electroporated full length mRNA encoding full length parental proteins to ensure that any observed T cell responses are specific for antigens that are naturally processed and presented. This technique can serve as useful experimental approach to determine the induction or enhancement of specific responses to naturally processed and presented antigens on HLA class I molecules in peripheral blood or tumor infiltrating T cells.