Delivery of exogenous antigen into the major histocompatibility complex class I and class II pathway by electroporation

Abstract: Exogenous, nonreplicating protein antigens (Ags) are usually taken up by antigen-presenting cells (APCs) via endocytosis or pinocytosis and enter the major histocompatibility complex (MHC) class II pro-cessing and presentation pathway. Although exogenous Ags are not processed and presented in the class I pathway by most cells, soluble proteins can enter the class I processing and presentation pathway if they are intro-duced directly into the cytoplasm of APCs. The purpose of these studies was to determine whether exogenous pro-teins could be processed and presented to T cells if they were delivered into cells by electroporation. The condi-tions for electroporation were optimized so that the via-bility of the electroporated cells was high5 and the majority of electroporated cells had protein incorporated. Electroporated B cells not only presented exogenous oval-bumin to CD8, class I MHC-restricted T cells but also stimulated CD4, class H MHC-restricted T cells. Elec-troporated cells also primed Ag-specific cytotoxic T lym-phocytes (CTLs) in vivo, stimulated CTL precursors in vitro, and served as target cells for lysis by Ag-specific CTLs, indistinguishable from transfected cells. Thus, electropermeabilized cells were structurally intact, and the introduced exogenous protein was processed and pre-sented in association with both class I and class II MHC molecules. This approach is as efficient and reproducible as other techniques of delivering exogenous proteins into the intracellular processing pathways. These studies sug-gest that electroporation could be employed for the study of cell-mediated immunity to various exogenous proteins