The present invention relates to the use of a microorganism or cell containing a DNA sequence encoding a desired polypeptide or RNA to induce autoimmunization of an organism against a tumor. Furthermore, the present invention relates to a method for the production of antibodies against a tumor comprising (a) injecting a microorganism or cell containing a DNA sequence encoding a desired polypeptide or RNA into an organism bearing a tumor and (b) isolating antibodies against the tumor.