Low calcium diet increases radical production of polymorphonuclear leukocytes from mice

Although calcium is an essential mineral for bones, little is known about its effect on inflammatory or oxidative regulation. We hypothesize that calcium plays the role in the production of reactive oxygen species (ROS) and nitric oxide (NO) from polymorphonuclear leukocytes (PMNs). Our purpose was to determine the relationship of NO and ROS produced from PMNs, taking into account the role of calcium and magnesium in diet. Using flow cytometry, we compared ROS and NO production from PMNs after the stimulation by S. aureus or phorbol myristate acetate (PMA). PMNs taken from three murine groups were analyzed: C57BL/6 wild-type mice, low-calcium diet (Low Ca Group), or low-magnesium diet fed for 2 weeks. ROS production at baseline in the Low Ca Group was highest among the groups. PMA- and S. aureus-stimulated ROS production was also highest in the Low Ca Group. On the contrary, NO production at baseline in the Low Ca Group was lowest among the groups, while there was no significant difference among the groups in S. aureus-stimulated PMNs. A low-calcium diet increases ROS production from stimulated PMNs and decreases NO production at baseline. This finding suggests that calcium regulates ROS production from PMNs.