A method of inducing a specific immune response in a mammal comprising: providing a first composition comprising isolated ubiquitinylated proteins in solution in the absence of membrane bound organelles the isolated ubiquitinylated proteins comprising one or more specific antigens and further comprising a threshold quantity of polyubiquitinylated short lived proteins and polyubiquitinylated defective ribosomal products. The isolated ubiquitinylated proteins are affinity purified from tumor derived cells grown in culture the tumor derived cells being inhibited from degrading ubiquitinylated proteins via the proteasome while being grown in culture. In this way highly immunogenic short lived proteins and defective ribosomal products may be loaded onto dendritic cells for cross presentation and priming of antigen specific T cells restricted by either classical or non classical MHC.
