Soon after Kohler and Milstein described the use of somatic cell hybridization for the production of murine monoclonal antibodies of desired specificity, this relatively simple technique became widely applied. Indeed, production of murine monoclonal antibodies is now considered routine by immunologists and nonimmunologists alike. However, as heterologous proteins, mouse monoclonal antibodies have one major limitation: they are immunogenic in man and, hence, their use in vivo is severely limited. An obvious solution to this problem is to produce human hybridomas with the same techniques used...