This invention provides novel methods of obtaining autologous monoclonal antibodies (AMABs) to self-antigens or homologs thereof. The method involves obtaining a genetically engineered host animal that does not biosynthesize at least one epitope of the antigen and utilizes the lack of self-tolerance of the host to the epitope to produce antibodies specific to the antigen. The invention also encompasses the AMABs produced by the methods. The invention further encompasses methods of isolating cells comprising the use of such AMABs that have specificity for a cell surface antigen.