Methods are disclosed for producing defective ribosomal products (DRiPs) in blebs (DRibbles) by contacting cells with a proteasome inhibitor, and in some examples also an autophagy inducer, thereby producing treated cells. DRibbles can be used to load antigen presenting cells (APCs), thereby allowing the APCs to present the DRiPs and antigenic fragments thereof. Immunogenic compositions that include treated cells, isolated DRibbles, or DRibble-loaded APCs are also disclosed. Methods are also provided for using treated cells, isolated DRibbles, or DRibble-loaded APCs to stimulate an immune response, for example in a subject. For example, DRibbles obtained from a tumor cell can be used to stimulate an immune response against the same type of tumor cells in the subject. In another example, DRibbles obtained from a pathogen-infected cell or cell engineered to express one or more antigens of a pathogen can be used to stimulate an immune response against the pathogen in the subject.
