Retroviruses and Hybridoma Formation

The fundamental technological step that led to the successful generation of monoclonal antibody-producing hybridomas was the fusion of mouse myeloma culture cells with specificity-sensitized mouse lymphocytes. Although the former cells contribute the capacity of eternal proliferation, the latter cells transfer to the newly created hybrid cells the capacity to produce antibodies of selected sensitivity (1). It is today widely known that myeloma cells also contribute the viral particles they carry to the progeny hybridoma cells (2–4), and at times so may the splenic lymphocytes. The fact that plasmacytoma cell lines carry and secrete retroviruses was already known in the 1960s, (5,6), but although these lines served only as substrates for laboratory experimentation, there was little concern with any resulting biohazard, except to a limited extent for the personnel handling the cells in the laboratory. In the first years following the discovery of hybridoma technology, the scientific and medical communities were so excited with the enormous potential of hybridoma research that little thought was given to detailed consideration of the cell lines used, other than the extent to which they might be useful for fusions and not interfere by producing undesired immunoglobulins of their own.