High magnesium concentration in vitro decreases human leukocyte activation

In view of experimental data suggesting that pharmacological magnesium (Mg) therapy could be expected to temper hypersensitivity, the aim of the present study was to assess the effect of in vitro high Mg concentration (8 mmol/l vs. 0.8 mmol/l) on human leukocyte activation. The first experiment in nine healthy volunteers was performed on total leukocyte suspension containing 82 +/- 4 per cent of neutrophils. The results demonstrate the inhibitory effect of high Mg concentration as shown by the significant reduction of superoxide anion production following phorbol myristate acetate (PMA) or formyl-methionyl-leucyl-phenylalanine (fMLP) activation. Moreover, neutrophils activated with fMLP showed an increased respiratory burst when incubated in low Mg concentration (0.2 mmol/l) as compared to normal Mg concentration (0.8 mmol/l). Similarly, high concentration of Mg resulted in a significant reduction in superoxide anion production by eosinophils in response to PMA in five eosinophilic patients. In patients showing Hymenoptera venom hypersensitivity, high Mg concentration resulted in a significant reduction of sulphidoleukotrienes production by leukocytes in response to venom allergen (six patients) or in response to zymosan activated particules (fourteen patients). Taken together, the results suggests that Mg acts via a non specific mechanism and appears to be non specific to a particular cell type. As Mg counteracts calcium in many physiological and pathological processes, it is reasonable to hypothesise that extracellular Mg can diminish leukocyte activation by its calcium antagonism.