 Initially, murine antibodies were obtained by hybridoma technology, for which Jerne, Köhler and Milstein received a Nobel prize.However the dissimilarity between murine and human immune systems led to the clinical failure of these antibodies, except in some specific circumstances.Major problems associated with murine antibodies included reduced stimulation of cytotoxicity and the formation complexes after repeated administration, which resulted in mild allergic reactions and sometimes anaphylactic shock.