title: Positive selection of hematopoietic CD34+ stem cells provides 'indirect purging' of CD34- lymphoid cells and the purging efficiency is increased by anti-CD2 and anti-CD30 immunotoxins.
abstract: Human CD34+ hematopoietic cells were purified using the avidin-biotin immunoabsorption technique. The selected population showed 78.6 +/- 3% CD34+ cells and the overall recovery of CD34+ cells, CFU-GM and BFU-E from the starting population was 34 +/- 5%, 71 +/- 4% and 67 +/- 2%, respectively. Hematopoietic progenitor cell purification also resulted in 3 log of normal T cell depletion from the bone marrow (BM) by immunofluorescence analysis. Moreover, when unseparated BM cells were mixed with the CD34- lymphoma cell lines D430B and Raji, the removal of greater than 3 log of tumor cells from the enriched CD34+ cell fraction was demonstrated. To increase the neoplastic cell purging, several immunotoxins (IT) containing the ribosome-inactivating protein (RIP) saporin and directed toward the lymphoid-associated antigens CD30 and CD2 were prepared. Our experiments showed only a minimal toxicity of the immunoconjugates on colony-forming cells (CFC) derived from purified CD34+ cells. Conversely, all the ITs were very effective in inhibiting protein synthesis and growth of normal and neoplastic lymphoid cells. Further experiments demonstrated that the sequential combination of CD34+ cells purification and IT treatment resulted in 5 or more log of tumor cell purging with no additional loss of BM progenitor cells.
authors.affiliation: Istituto di Ematologia Seragnoli, Università di Bologna, Italy.
authors.forename: R M
authors.initials: RM
authors.lastname: Lemoli
authors.forename: P L
authors.initials: PL
authors.lastname: Tazzari
authors.forename: A
authors.initials: A
authors.lastname: Fortuna
authors.forename: A
authors.initials: A
authors.lastname: Bolognesi
authors.forename: S C
authors.initials: SC
authors.lastname: Gulati
authors.forename: F
authors.initials: F
authors.lastname: Stirpe
authors.forename: S
authors.initials: S
authors.lastname: Tura
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis / Q000276:immunology*; D016465:Bone Marrow Purging / Q000379:methods*; D018801:CD2 Antigens; D002469:Cell Separation / Q000379:methods*; D003602:Cytotoxicity, Immunologic; D006412:Hematopoietic Stem Cells / Q000737:chemistry; D006801:Humans; D007163:Immunosorbent Techniques; D000922:Immunotoxins / Q000494:pharmacology*; D017730:Ki-1 Antigen / Q000032:analysis / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects; D009699:N-Glycosyl Hydrolases; D010940:Plant Proteins / Q000494:pharmacology*; D014176:Protein Biosynthesis; D011971:Receptors, Immunologic / Q000032:analysis / Q000276:immunology*; D054789:Ribosome Inactivating Proteins, Type 1; D000076985:Saporins
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D000922:Immunotoxins; D017730:Ki-1 Antigen; D010940:Plant Proteins; D011971:Receptors, Immunologic; D054789:Ribosome Inactivating Proteins, Type 1; D009699:N-Glycosyl Hydrolases; D000076985:Saporins