title: Ex vivo expansion of CD56+ cytotoxic cells from human umbilical cord blood.
abstract: The immune-mediated effect of natural killer (NK) and cytotoxic T cells against residual tumor cells previously was shown to prevent relapse and reinduce remission after bone marrow transplantation. Human umbilical cord blood is a rich source of cytotoxic CD56+ cells including fetal NK cells (CD16(-)CD56+1) with high lytic capabilities upon activation with interleukin-2 (IL-2). Cord blood transplantations are reported to be associated with lower risk of graft-vs-host disease, which may jeopardize the graft-vs-leukemia effect. Therefore, our goal was to expand and amplify, ex vivo, cord blood-derived CD56+ cell-mediated cytotoxic activity. Cord blood-derived CD56+ cells were separated using anti-CD56 monoclonal antibody and immunomagnetic beads. The cells were expanded in the presence of irradiated feeder cells and various concentrations of IL-2. Maximal fold expansion (152 +/- 29) was achieved on day 22 by culturing the cells in the presence of irradiated autologous lymphocytes. Irradiated murine stromal cells yielded 42 +/- fourfold expansion (p < 0.05). FACS analysis at the peak of expansion revealed that the cells were 96% +/- 1% CD56+. Interferon-gamma levels significantly decreased throughout the culture period (from 1,034 +/- 34 pg/mL to 21 +/- 8 pg/mL) as did IL-6 levels (from 11,535 +/- 1,452 pg/mL to 323 +/- 161 pg/mL) whereas tumor necrosis factor-alpha levels did not change. The expanded cells manifested potent lytic capabilities against K562 and Colo-205 cell lines (70.9% +/- 2.0% and 48.2% +/- 4.0%, respectively) (n = 5) (effector-to-target ratio 25:1). Coculturing the expanded NK cells with fresh ALL blasts resulted in 85% +/- 1% inhibition of colony growth in methylcellulose (n = 2). In addition, the CD56+ expanded cells induced 44% +/- 7.5% apoptosis of K562 target cells (n = 3). It is possible to effectively expand cord blood-derived CD56+ cells, ex vivo, while maintaining their antileukemic capablilities.
authors.affiliation: Department of Bone Marrow Transplantation, Hadassah University Hospital, Jerusalem, Israel 91120.
authors.forename: R
authors.initials: R
authors.lastname: Condiotti
authors.forename: Y B
authors.initials: YB
authors.lastname: Zakai
authors.forename: V
authors.initials: V
authors.lastname: Barak
authors.forename: A
authors.initials: A
authors.lastname: Nagler
mesh_terms: D000818:Animals; D017209:Apoptosis; D019002:CD56 Antigen / Q000032:analysis*; D018929:Cell Culture Techniques / Q000379:methods; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects; D018920:Coculture Techniques; D003110:Colonic Neoplasms / Q000473:pathology; D003601:Cytotoxicity Tests, Immunologic; D005312:Fetal Blood / Q000166:cytology*; D005434:Flow Cytometry; D006801:Humans; D018189:Immunomagnetic Separation; D016130:Immunophenotyping; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism; D020014:K562 Cells / Q000473:pathology; D007694:Killer Cells, Natural / Q000737:chemistry / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000473:pathology; D051379:Mice; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000473:pathology; D017154:Stromal Cells / Q000166:cytology / Q000528:radiation effects; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D019002:CD56 Antigen; D007376:Interleukin-2; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma