The present invention relates to a method of vaccination or immunisation involving the use of a photosensitizing agent, an antigenic molecule, e.g. a vaccine component, and an agent which enhances the effect of photochemical internalization (PCI)-mediated vaccination wherein the agent is a ligand for a Toll-like receptor (TLR) as defined herein, and irradiation with light of a wavelength effective to activate the photosensitizing agent. The invention also relates to antigenic, e.g. vaccine compositions, useful in such a method. The invention also provides a method of generating antigen presenting cells which may be used to generate an immune response, e.g. for vaccination, which involves using the same components as above to introduce antigenic molecules, e.g. vaccine components, into cells to achieve antigen presentation, and to antigenic compositions useful in such a method. The invention also provides use of cells generated in vitro by such methods for administration to a patient in vivo to elicit an immune response, e.g. to achieve vaccination. A method of internalising an antigenic molecule into a cell is also provided.
