EFFECTIVE REMOVAL OF SCLC CELLS FROM HUMAN BONE-MARROW - USE OF 4 MONOCLONAL-ANTIBODIES AND IMMUNOMAGNETIC BEADS

High dose chemotherapy with autologous bone marrow transplantation (AB MT) has shown promise in several types of cancer. There is, however, a risk of transfusing contaminating tumour cells with the bone marrow c ells, e.g. in patients with small cell lung carcinoma (SCLC). To elimi nate SCLC cells from normal human bone marrow, four monoclonal antibod ies reactive with SCLC cells were used with immunomagnetic beads in mo del experiments. With two cycles of immunomagnetic elimination the ind ividual antibodies removed 2.5 -4.4 log of H- 1 46 tumour cells from a single cell suspension, as assessed in a highly reproducible soft aga r assay. Different combinations of two antibodies were only marginally more effective than the individual MAbs, whereas 5 -6 log removal was obtained with a combination of all four antibodies. The method was eq ually effective when the tumour cells were mixed with bone marrow cell s at a ratio of 1:10. The immunomagnetic procedure did not significant ly affect the survival of normal progenitor cells, assessed in CFU-GM and CFU-GEMM assays. The results indicate that the procedure safely an d effectively can be used to eliminate tumour cells from the bone marr ow in conjunction with ABMT in patients with SCLC.