This invention relates to methods and compositions useful for delivering antigens to dendritic cells which are then useful for inducing antigen-specific cytotoxic T lymphocytes and T helper cells. This invention also provides assays for evaluating the activity of cytotoxic T lymphocytes. According to the invention, antigens are targeted to dendritic cells by apoptotic cells which may also be modified to express non-native antigens for presentation to the dendritic cells. The dendritic cells which are primed by the apoptotic cells are capable of processing and presenting the processed antigen and inducing cytotoxic T lymphocyte activity or may also be used in vaccine therapies.