PERIPHERAL-BLOOD CD34-CANCER PATIENTS - EFFECT ON HEMATOPOIETIC PROGENITOR CONTENT AND HEMATOLOGIC RECOVERY AFTER HIGH-DOSE CHEMOTHERAPY AND AUTOTRANSPLANTATION( CELL IMMUNOMAGNETIC SELECTION IN BREAST)

BACKGROUND: Tumor cells have been detected in mobilized peripheral blo od of breast cancer patients, and they may contribute to tumor recurre nce after the transplantation of peripheral blood progenitor cells. On e of the most widespread technologies for tumor purging of the graft i s immunomagnetic hematopoietic progenitor cell selection. STUDY DESIGN AND METHODS: The study assessed the effectiveness of a magnetic cell- separation system in selecting functional subpopulations of hematopoie tic progenitors from 14 blood-derived harvests of 11 patients with hig h-risk breast cancer after mobilization following cytotoxic chemothera py supported by granulocyte-colony-stimulating factor, as well as the feasibility of transplanting these selected subpopulations. RESULTS: C D34+-enriched cell fractions had a median purity of 93.0 percent (72.7 -98.5%). The procedure yielded 52.6 percent of the CD34+ cell input (3 9.4-116.8%). Median recoveries of colony-forming units (CFUs) (36.87%) and cobblestone area-forming cells (CAFCs) (152.5%) were, respectivel y, 0.70 and 2.87 times those of CD34+ cells (52.6%). Moreover, CAFC ef ficiency in the positive cell fraction was 2.57 times that in the star ting cell fraction. Peripheral blood neutrophil counts of 0.5 x 10(9) per L and platelet counts of 20 x 10(9) per L were reached after media n times of 9 and 11 days, respectively. The number of transfused CAFCs per kg, CD34+ cells per kg, and postthaw CFU-granulocyte-macrophage p er kg was correlated, respectively, with the speed of engraftment of n eutrophils, platelets, or both. Tumor cells detected in one patient's peripheral blood were not found after CD34+ cell selection. CONCLUSION : Transplantation of immunomagnetically purified peripheral blood CD34 + cells does not increase transplantation-related morbidity. It induce s a selective enrichment of more immature hematopoietic progenitors, w hich makes it suitable for use in cell expansion and gene therapy prot ocols.