Ex vivo expansion of CD56 + cytotoxic cells from human umbilical cord blood

• Published in: Experimental hematology Vol. 29; no. 1; pp. 104 - 113
• Main Authors: Condiotti, Reba, Zakai, Yifat Bar, Barak, Vivian, Nagler, Arnon
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 2001
• Subjects: Animals; Apoptosis; CD56 Antigen - analysis; Cell Culture Techniques - methods; Cell Division - drug effects; Cells, Cultured - drug effects; Coculture Techniques; Colonic Neoplasms - pathology; Cord blood; Cytokines; Cytotoxic cells; Cytotoxicity Tests, Immunologic; Expansion; Fetal Blood - cytology; Flow Cytometry; Humans; Immunomagnetic Separation; Immunophenotyping; Infant, Newborn; Interferon-gamma - secretion; Interleukin-2 - pharmacology; Interleukin-6 - secretion; K562 Cells - pathology; Killer Cells, Natural - chemistry; Killer Cells, Natural - cytology; Killer Cells, Natural - drug effects; Killer Cells, Natural - secretion; Leukemia-Lymphoma, Adult T-Cell - pathology; Mice; Precursor Cell Lymphoblastic Leukemia-Lymphoma - pathology; Stromal Cells - cytology; Stromal Cells - radiation effects; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha - secretion; Cytotoxic cells; Cord blood; Cytokines; Expansion; Apoptosis
• ISSN: 0301-472X; 1873-2399
• DOI: 10.1016/S0301-472X(00)00617-2

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-γ 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-α 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.