On August 7, 1975, Kohler and Milstein published in Nature (256:495) a report describing "Continuous cultures of fused cells secreting antibody of predefined specificity. " Their report has become a classic and has already had a profound effect on basic and applied research in biology and medicine. By the time the first Workshop on Lymphocyte Hybridomas (Current Topics in Microbiology and Im munology 81, 1978) was held on April 3-5, 1978, in Bethesda, Maryland, investi gators from many laboratories had made hybrids between plasmacytomas and spleen cells from immunized animals and had obtained...