Elimination of small cell lung cancer cells in vitro from human bone marrow by a monoclonal antibody.

We report here a useful method for elimination of small cell lung cancer cells in vitro from bone marrow. A monoclonal antibody, TFS-2, which mediates complement lysis and recognizes an antigen present on small cell lung cancer cells but not lymphoid cells or bone marrow cells, was used to clear infiltrated bone marrow. The antibody in the presence of complement effectively killed tumor cells, but it was not cytotoxic to bone marrow cells. When mixed populations consisting of tumor cells and bone marrow cells were treated with antibody and complement, the tumor cells were also effectively killed, except when large numbers of bone marrow cells were present, whereas TFS-2 had no significant effect on bone marrow stem cells, as judged by colony-forming unit assays.