title: Flow cytometry to estimate circulating hematopoietic progenitors for autologous transplantation: comparative analysis of different CD34 monoclonal antibodies.
abstract: We report that the 2 fluorescein (FITC) conjugated CD34 monoclonal antibodies available to date, namely FITC-8G12 and FITC-QBEND10, exhibit different capabilities of detecting circulating hematopoietic progenitors (CHP) as cells expressing the CD34 antigen (CD34+) by direct immunofluorescence flow cytometry. Mean fluorescence intensity conferred by FITC-QBEND10 to CD34+ CHP is 2.8-4.3 times lower than that conferred by FITC-8G12. By indirect immunofluorescence, native unconjugated QBEND10 and 8G12 antibodies detect CD34+ CHP in a comparable manner, thus indicating that the decrease in QBEND10 affinity is due to FITC-conjugation. Utilization of FITC-QBEND10 instead of FICT-8G12 to estimate infrequent (usually less than or equal to 5%) CD34+ CHP for clinical decision-making in autologous transplantation of CHP exposes clinicians to the risk of either overestimating (false positive) or underestimating (false negative) these cells in peripheral blood. Recently published guidelines for large-scale collection of CHP for autologous transplantation in cancer patients were based on data obtained with FITC-8G12. The same guidelines cannot be considered valid if FITC-QBEND10 is employed. We recommend FITC-8G12 as the optimal reagent to date for standardizing results of autologous CHP transplantation in cancer therapy.
authors.affiliation: Cristina Gandini Transplantation Unit, Istituto Nazionale Tumori, Milano, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Siena
authors.forename: M
authors.initials: M
authors.lastname: Bregni
authors.forename: B
authors.initials: B
authors.lastname: Brando
authors.forename: N
authors.initials: N
authors.lastname: Belli
authors.forename: P M
authors.initials: PM
authors.lastname: Lansdorp
authors.forename: G
authors.initials: G
authors.lastname: Bonadonna
authors.forename: M
authors.initials: M
authors.lastname: Gianni
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D015703:Antigens, CD / Q000032:analysis*; D018952:Antigens, CD34; D001772:Blood Cell Count / Q000379:methods*; D001804:Blood Transfusion, Autologous; D001943:Breast Neoplasms / Q000097:blood; D002469:Cell Separation; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D005455:Fluorescent Antibody Technique; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology / Q000627:therapeutic use; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007377:Interleukin-3 / Q000008:administration & dosage / Q000627:therapeutic use; D011237:Predictive Value of Tests; D011994:Recombinant Proteins / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018952:Antigens, CD34; D007377:Interleukin-3; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D016650:Fluorescein-5-isothiocyanate