Depletion of T lymphocytes from human bone marrow. Use of magnetic monosized polymer microspheres coated with T-lymphocyte-specific monoclonal antibodies.

A new technique for depletion of T cells from bone marrow is presented. Bone marrow cells (BMC) were rosetted with magnetic monosized polystyrene microspheres coated with monoclonal antibodies (MAbs) specific for T cell CD2 and CD3 antigens. Rosetted T cells were subsequently removed from non-T cells with the aid of a magnet. This immunomagnetic separation procedure was carried out in less than 40 min and reproducibly removed T cells, leaving a maximum of 0.025% sheep-red-blood-cell (SRBC) rosette-forming cells and less than 0.02% T cells as detected by a T cell limiting dilution assay. The efficacy of the depletion procedure was further shown by flow cytometry data, by effective removal of cells from a T cell line added to the BMC prior to immunomagnetic separation, and by abrogation of interleukin 2 (IL-2)-producing capacity in T-cell-depleted BMC (BMC-T). The T cell depletion procedure provided a 43-74% recovery of non-T cells present in the Isopaque-Ficoll-isolated bone marrow mononuclear cell fraction and did not disturb the growth potential of stem cells, as assayed by hematopoietic stem cell assays.