Immunomagnetic manipulation of bone marrow and tumour cells: an update.

The immunomagnetic separation procedure for the separation of neuroblasts from bone marrow harvested for autologous transplantation was first described in 1983 (Treleaven et al., 1984). In the intervening period, the technique has been extended to other tumours and modified by several laboratories. In addition, the procedure has been used for the separation of different mammalian cell types (Nilsson et al., 1987), micro-organisms (Lund et al., 1988) and at the subcellular level, organelles (Howell et al., 1988), and DNA (Dudin et al., 1988). Although immunomagnetic separation techniques have been used extensively for bone marrow purging, the recovery of cells from the matrix has remained problematical. This manuscript is intended to offer an update on our experiences in the use of the immunomagnetic purging procedure. In addition, more detailed basic studies have been undertaken to characterize further the antigens recognized by the antibodies for the removal of neuroblasts from bone marrow. The information obtained in these studies may, in part, explain why it is intrinsically more difficult to separate neuroblasts from the magnetic matrix than haematopoietic cells such as either T or acute lymphoblastic leukaemic cells.