POSITIVE SELECTION OF CD34(-CELLS USING AN IMMUNOAFFINITY COLUMN RESULTS IN T CELL-DEPLETION EQUIVALENT TO ELUTRIATION() HEMATOPOIETIC)

Acute graft-vs.-host disease (GVHD) continues to present a barrier to successful allogeneic marrow transplantation. T cell-depletion may pre vent severe GVHD but carries an increased risk of graft rejection and relapse posttransplant. Clinical trials have defined the number of lym phocytes associated with sustained engraftment but low risk of signifi cant GVHD (greater than grade I or II skin only) as less than or equal to 10(5)/kg. We examined T cell-depletion resulting from positive sel ection of CD34(+) hematopoietic cells with a biotinylated monoclonal a nti-CD34 antibody and an immunoaffinity column. Eleven patients (six m yeloma and five breast cancer) underwent both peripheral blood stem ce ll (PBSC) collection and marrow harvest prior to autologous transplant ation. One PBSC collection and one-third of each marrow underwent colu mn separation. PBSCs were enriched for CD34(+) cells from an initial m ean of 1.5 to 53.3%, while marrow went from an initial mean of 2.8 to 65.4%. PBSC were depleted of CD3(+) cells from an initial mean of 9.6 x 10(9) to 8.6 x 10(6). Marrow CD3(+) lymphocyte content was reduced f rom an initial mean of 5.6 x 10(9) to 8 x 10(5). Since the column perm its quantification and salvage of depleted T cells, its use should all ow re-addition of T cell-aliquots associated with minimal risk for GVH D and rejection. In addition, since PBSCs were as readily depleted as marrow, allogeneic PBSC transplant may be feasible using this method.