Role of antigen-presenting cells in cross-priming of cytotoxic T lymphocytes by apoptotic cells

Although the mechanisms regulating recognition and phagocytosis of apoptoti c cells by scavenger cells ape the subject of intense investigation, little is known about the fate of the antigens contained in apoptotic cells and t he constraints defining their immunogenicity, We developed a model in C57BL /6 mice to evaluate whether phagocytosis of apoptotic tumor cells yielded a ntigens able to get access to the MHC class I pathway and activate a specif ic cytotoxic T lymphocyte response. Our results demonstrate that apoptotic tumor cells are antigenic in, vitro and can be immunogenic in vivo. Their i mmunogenicity depends on the number of cells used for immunization and the antigen-presenting cells involved in processing and presentation of antigen s contained in the dying cells. The demonstration of the immunogenicity of apoptotic cells may have direct implications both in autoimmunity and cance r.