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Updated: Aug 18, 2026
Colony Forming Cell (CFC) Assay for Human Hematopoietic Cells
Published on: December 18, 2010
Differentiation of human U937 promonocytic cells is impaired by moderate copper deficiency
Z L Huang1, M L Failla, P G Reeves
1Graduate Program in Nutrition, The University of North Carolina at Greensboro, 27402, USA.
Abstract:
Copper (Cu) deficiency suppresses macrophage activities in animals and humans. Our previous studies indicated that the induction of Cu deficiency in differentiated U937 monocytic cells impairs respiratory burst and bactericidal activities and lipopolysaccharide-mediated secretion of inflammatory mediators. The current investigation examined the roles of Cu in the monocytic differentiation process. Human U937 promonocytic cells were exposed to a high affinity Cu chelator (5 microM 2,3,2-tetraamine [tet]) for 24 hr before inducing differentiation by treatment with 1,25-dihydroxyvitamin D3 plus interferon-gamma (DI). This procedure decreased cell Cu by 55% without compromising cellular Zn, Fe, or general metabolic activities. Lower Cu status significantly attenuated the expression of maturation markers Mac-1 (CD11b), ICAM-1 (CD54), and LPS-R (CD14). This change was associated with a marked suppression in respiratory burst activity and killing of Salmonella. To examine if the adverse effect of inadequate Cu on the DI-induced differentiation represented a more general defect, U937 cells were treated with phorbol 12-myristate 13-acetate (PMA). Lower Cu status also suppressed PMA-mediated differentiation of U937 cells. Supplemental Cu, but not Zn or Fe, blocked the tet-induced declines in cell Cu, expression of maturation markers, and respiratory burst and bactericidal activities. These results demonstrate that Cu is essential for the monocytic differentiation process that contributes to the competency of the host's defense system.
Insights
Copper is essential for macrophage development and function. This study shows copper deficiency impairs monocytic differentiation, hindering the host
Area of Science:
- Immunology
- Nutritional Biochemistry
Background:
- Copper (Cu) deficiency is known to impair macrophage functions, including respiratory burst and bactericidal activities.
- Previous research indicated that Cu deficiency in differentiated U937 monocytic cells affects inflammatory responses.
Purpose of the Study:
- To investigate the role of copper in the monocytic differentiation process.
- To determine if copper is essential for U937 cell maturation into macrophages.
Main Methods:
- Human U937 promonocytic cells were treated with a copper chelator (2,3,2-tetraamine [tet]) to induce copper deficiency.
- Differentiation was induced using 1,25-dihydroxyvitamin D3 plus interferon-gamma (DI) or phorbol 12-myristate 13-acetate (PMA).
- Cellular copper levels, expression of maturation markers (Mac-1, ICAM-1, LPS-R), respiratory burst activity, and bacterial killing were assessed.
Main Results:
- Copper deficiency significantly reduced cellular copper levels by 55% without affecting zinc, iron, or general metabolic activity.
- Reduced copper status attenuated the expression of key monocytic maturation markers.
- Copper deficiency suppressed both DI- and PMA-induced U937 cell differentiation, impairing respiratory burst and Salmonella killing.
- Supplemental copper, but not zinc or iron, reversed these suppressive effects.
Conclusions:
- Copper is essential for the proper monocytic differentiation of U937 cells.
- Adequate copper status is critical for the development of functional macrophages involved in host defense.
- These findings highlight the importance of copper in maintaining immune competency.
