Elimination of bcl-2-IgH-positive follicular lymphoma cells from blood transplants with high recovery of hematopoietic progenitors by the miltenyi CD34+ cell sorting system

Contamination of autologous blood cell transplants with cells of follicular non-Hodgkin's lymphoma (F-NHL) may contribute to relapse of the malignancy after potentially curative high doses of chemotherapy and radiotherapy. In an attempt to circumvent this limitation, we have evaluated various techniques of selection of CD34+ cells to eliminate malignant cells from blood cell transplants of five patients with F-NHL undergoing high-dose sequential therapy. The contamination of F-NHL cells was evaluated using a nested PCR assay for the detection of bcl-2-IgH rearrangement with a sensitivity of one F-NHL cell in 10(5) normal cells. In two experiments with blood cell transplant fractions of 0.5 x 10(9) nucleated cells, negative selection of CD34+ cells by removal of B cells and other mature cells that naturally adhere to nylon wool fibers decreased the number of CD19+ B cells detectable by flow cytometry but failed to eliminate bcl-2-IgH-positive F-NHL cells detectable by PCR. In contrast, positive selection of CD34+ cells by the Miltenyi MiniMACS high gradient magnetic cell sorting system in five separate experiments resulted in: (1) the elimination of F-NHL cells in four out of five cases as detected both flow cytometry and bclk-2-IgH PCR; (2) a highly purified population of hematopoietic progenitors comprising 90.8% +/- 2.3% CD34+ cells; and (3) the recovery of 77.9% +/- 3.2% CD34+ cells. These favorable results were confirmed on a large-scale with a blood cell transplant comprising 5.8 x 10(9) nucleated cells in which positive selection of CD34+ cells by the Miltenyi SuperMACS system resulted in: (1) the elimination of F-NHL cells as detected both by flow cytometry and bcl-2-IgH PCR; (2) a highly purified population of hematopoietic progenitors comprising 94.6% CD34+ cells; and (3) the recovery of 62.7% CD34+ cells. These results, attained with the newly available Super MACS system, compare favorable with previous techniques because they show the feasibility of eliminating F-NHL cells from blood cell transplants without relevant nonspecific loss of hematopoietic progenitors.