title: Selection of stem cells by using antibodies that target different CD34 epitopes yields different patterns of T-cell differentiation.
abstract: The objective of this study was to compare the patterns of T-cell differentiation from CD34(+) human stem cells selected with different classes of antibody targeting the CD34 molecule. We compared signal-joint T-cell receptor excision circle (sjTREC) production in thymocytes selected with different classes of anti-CD34 antibody. Based on these results, we studied immune reconstitution in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice using human stem cells selected with the same antibodies that yielded variation in the thymocytes. Human CD34(+) stem cells were immunomagnetically selected using the class II QBEnd antibody (prevalent in clinical graft engineering) and the class III 8G12 antibody (common in diagnostic tests). Engraftment and T-cell reconstitution were examined after transplantation. Thymocytes selected with the 8G12 class III antibody have a higher TREC production than those selected with the QBEnd class II antibody. Of mice transplanted with cells selected using the 8G12 antibody, 50% had sjTREC production, compared with 14% of mice transplanted with cells selected using the clinically common antibody QBEnd. 8G12 thymic progenitors are characterized by higher quality in thymic distribution and higher activity in T-cell differentiation. Using class III antibody targeting the CD34 molecule resulted in increased T-cell reconstitution in the NOD/SCID mouse. Use of a single antibody epitope targeting the CD34 molecule may lead to loss of cells that might provide richer T-cell reconstitution. Use of different or multiple epitopes, targeting of alternate stem cell markers, or use of cell-depletion strategies might prevent this loss.
authors.affiliation: Division of Stem Cell Transplantation, Department of Hematology/Oncology, St. Jude Children's Research Hospital, 332N Lauderdale Street, Memphis, Tennessee 38105-2794, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Otto
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Chen
authors.forename: William J
authors.initials: WJ
authors.lastname: Martin
authors.forename: Wing
authors.initials: W
authors.lastname: Leung
authors.forename: James
authors.initials: J
authors.lastname: Knowles
authors.forename: Marti
authors.initials: M
authors.lastname: Holladay
authors.forename: Jim
authors.initials: J
authors.lastname: Houston
authors.forename: Rupert
authors.initials: R
authors.lastname: Handgretinger
authors.forename: Raymond C
authors.initials: RC
authors.lastname: Barfield
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology*; D018952:Antigens, CD34 / Q000276:immunology*; D001853:Bone Marrow; D002454:Cell Differentiation; D002648:Child; D002675:Child, Preschool; D000939:Epitopes / Q000276:immunology*; D005434:Flow Cytometry; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007223:Infant; D017493:Leukocyte Common Antigens / Q000276:immunology; D051379:Mice; D016513:Mice, SCID; D011948:Receptors, Antigen, T-Cell / Q000096:biosynthesis; D013234:Stem Cells / Q000166:cytology* / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology
chemical_list: D000906:Antibodies; D018952:Antigens, CD34; D000939:Epitopes; D011948:Receptors, Antigen, T-Cell; D017493:Leukocyte Common Antigens