Aim: To evaluate the ability of anti-ricin A-chain antibodies, delivered intracellularly, to protect against ricin-induced cytotoxicity in RAW264.7 cells.
Methods: Anti-deglycosylated ricin A-chain antibody and RAC18 anti-ricin A-chain monoclonal antibody were delivered intracellularly by encapsulating in liposomes or via conjugation with the cell-penetrating MTS-transport peptide. RAW264.7 cells were incubated with these antibodies either before or after ricin exposure. The changes in cytotoxicity were estimated by MTT assay. Co-localization of internalized antibody and ricin was evaluated by fluorescence microscopy.
Results: Internalized antibodies significantly increased cell viability either before or after ricin exposure compared to the unconjugated antibodies. Fluorescence microscopy confirmed the co-localization of internalized antibodies and ricin inside the cells.
Conclusion: Intracellular delivery of antibodies to neutralize the ricin toxin after cellular uptake supports the potential use of cell-permeable antibodies for post-exposure treatment of ricin intoxication.
Keywords: Antibody internalization; Cell-penetrating peptide; Cell-permeable antibodies; Liposome-encapsulated antibodies; Ricin inhibitors.