The present invention relates to a method for identifying peptides involved in immunogenicity comprising the steps of a) providing cells expressing antigen presenting receptors (APR) in a number providing 0.1 to 5 ug of APR molecules, b) contacting the cells from (a) with a source of immunogenic peptides, c) isolating APR molecule-immunogenic pep tide complexes from the cells, d) eluting the associated peptides from the APR molecules, e) identifying the immunogenic peptides, and f) verifying the identified immunogenic peptides as epitopes.