“…(27) As potential substitutes for human antibodies, and as model system s for the development of hum an fusions, primates have also received much attention, and antibodies have been developed in chimpanzees, (28)(29)(30) baboons, (28) and several species of macaque monkey. (28,(31)(32)(33)(34) The motivation for developing rat MAbs, (35) and to some extent hamster MAbs, (3 6,37) has been primarily the search for antibodies to endogenous murine antigens or antigens that produce poor responses in mice. The production of MAbs from rabbits (38)(39)(40)(41) and guinea pigs (42 ,43) has proved to be considerably more difficult, and, although som e immunoglobu lin fragment and intact rabbit antibodies have been reported from interspecific fusions, a most significant advance has been the development of a rabbit plasmacytoma fusion partner.…”