Influence of oxygen partial pressure on human and mouse myeloid cell line characteristics

Mouse and human cells have been reported to have different thiol characteristics (J. M. Messina and D. A. Lawrence, 1992, Int. J. Immunopharmacol. 14, 1221-1234). In addition, when cells are undergoing active growth, they usually have an increased thiol content. In an attempt to determine whether a mouse and a human cell line with similar characteristics can be induced to change their phenotype simply by being cultured at a lower oxygen partial pressure (pO2), the human KG-1 and mouse M1 myeloid cell lines were cultured at 5 and 20% oxygen. It is important to note that 5% O2 is close to the physiological pO2, whereas the percentage of O2 usually employed for most in vitro methods is atmospheric pO2. After long-term culturing at 5% (L cell lines) versus 20% O2 (H cell lines), the thiol content of the original (H) cell lines significantly changed. The amount of total and surface thiols was lower in both L cell lines, but only significantly different on the M1 lines, whereas the glutathione content was significantly lower in the L cell lines of KG-1 and M1. The mouse lines showed the greatest sensitivity to pO2 changes; however, the mouse cell lines were not more sensitive to hydrogen peroxide than the human cell lines even though they possess significantly less total thiols and glutathione. Interestingly, cell lines maintained at lower pO2 (physiological pO2) were more sensitive to hydrogen peroxide than their parental counterparts that were maintained at atmospheric oxygen levels.