Abstract
The human THP-1 cell line is widely used as an in vitro model system for studying macrophage differentiation and function. Conventional culture conditions for these cells consist of ambient oxygen pressure (∼20% v/v) and medium supplemented with the thiol 2-mercaptoethanol (2-ME) and serum. In consideration of the redox activities of O2 and 2-ME, and the extensive experimental evidence supporting a role for reactive oxygen species (ROS) in the differentiation and function of macrophages, we addressed the question of whether culturing THP-1 cells under a more physiologically relevant oxygen tension (5% O2) in the absence of 2-ME and serum would alter THP-1 cell physiology. Comparisons of cultures maintained in 18% O2 versus 5% O2 indicated that reducing oxygen tension had no effect on the proliferation of undifferentiated THP-1 cells. However, decreasing the oxygen tension to 5% O2 significantly increased the rate of phorbol ester-induced differentiation of THP-1 cells into macrophage-like cells as well as the metabolic activity of both undifferentiated and PMA-differentiated THP-1 cells. Removal of both 2-ME and serum from the medium decreased the proliferation of undifferentiated THP-1 cells but increased metabolic activity and the rate of differentiation under either oxygen tension. In differentiated THP-1 cells, lowering the oxygen tension to 5% O2 decreased phagocytic activity, the constitutive release of β-hexosaminidase and LPS-induced NF-κB activation but enhanced LPS-stimulated release of cytokines. Collectively, these data demonstrate that oxygen tension influences THP-1 cell differentiation and primary macrophage functions, and suggest that culturing these cells under tightly regulated oxygen tension in the absence of exogenous reducing agent and serum is likely to provide a physiologically relevant baseline from which to study the role of the local redox environment in regulating THP-1 cell physiology.
Highlights
While it is widely accepted that immortalized cell lines do not exactly replicate primary human cells, cell lines can be extremely powerful experimental models and are generally more widely accessible to the research community than primary human cells
Our studies indicate that altering the oxygen tension significantly influences THP-1 cell physiology, whereas omitting 2-ME and serum from the culture medium has minimal impact
While there are limitations associated with cell lines, those that have been immortalized and express significant mutations that may alter the physiology of these cells relative to the primary cell type from which they were derived, cell lines, those of human origin such as the THP-1 cell line, are especially useful for pilot projects, drug and toxicity screening, biochemical studies of signal transduction pathways and other types of studies that require large number of cells
Summary
While it is widely accepted that immortalized cell lines do not exactly replicate primary human cells, cell lines can be extremely powerful experimental models and are generally more widely accessible to the research community than primary human cells. 2-ME was originally added to media used to culture murine lymphocytes to increase intracellular levels of reduced glutathione and thereby enhance cellular functions [5]; ME does not enter the cells freely but does increase uptake of Cys which may result in increased GSH synthesis. This practice has since been adopted and recommended for culturing diverse cell types derived from multiple species, including human THP-1 cells, with little experimental evidence to support its value in enhancing cell viability and/or cell-specific functions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
