Most studies of biosynthesis were performed with plasmacytoma cell to avoid the problem of polyclonal responce with different immunoglobulins with plasmacytomas, however one does not find a range of antibody specificitis. as a result immunologis for some time had saught methods whereby continous cultures of cell produced a mono clonal antibody against a defined antigen. This aim has been partly reached with the development of lymphocyte hybridomas.