IMMUNOMAGNETIC SELECTION OF CD34(-BLOOD STEM-CELLS FOR AUTOGRAFTING IN PATIENTS WITH BREAST-CANCER() PERIPHERAL)

Contamination of transplants with tumour cells may contribute to relap se after peripheral blood stem cell transplantation (PBSCT). We studie d the feasibility of CD34(+) cell selection from blood-derived autogra fts obtained following G-CSF-supported cytotoxic chemotherapy in a gro up of 25 patients with breast cancer (10 with high-risk stage II/III a nd 15 with stage IV without bone or bone marrow involvement). Using im munomagnetic beads (Isolex 300 SA, Baxter) CD34(+) cells were enriched and released by chymopapain resulting in a median purity of 95% (rang e 82-99%) and a median recovery of 80% (range 27-132%), The enrichment procedure did not change the proportion of CD34(+) subsets coexpressi ng HLA-DR, CD38 and Thy-1, while L-selectin was removed from the cell surface following selection. Using a sensitive immunocytological techn ique with a cocktail of epithelial-specific antibodies (anti-cytokerat in 8, 18 and 19; HEA125; BM7 and BM8), we leukaphereses products conta ined epithelial cells, whereas the selected CD34(+) cell fraction was free of tumour cells. A neutrophil count of 0.5 x 10(9)/l and a platel et count of 20 x10(9)/l was reached after a median time of 14 and 10d following 40 high-dose chemotherapy (HDC) cycles, Our results indicate that immunomagnetic selection of CD34(+) cells yields highly purified autografts devoid of tumour cells whereas the engraftment ability of the progenitor and stem cells is fully retained.