Static magnetic field interferes with macrophage phagocytosis

Increasing evidences suggest that static magnetic fields (SMFs) are capable to affect a number of biological functions, including monocyte/macrophage differentiation. Indeed, we found that the presence of 6mT SMF interferes with monocyte/macrophage TPA-induced differentiation of promonocytes U937 and monocytes THP-1 cells, respectively of a 20% increment and a 15% decrement. During the monocyte/macrophage differentiation cells progressively acquire the ability to internalize and finally become active phagocytes. Fluid phase endocytosis and phagocytosis of latex particles and apoptotic cells in TPA-induced U937 and THP1 cells were studied in the presence of 6 mT SMF. Phagocytosis but not fluid phase endocytosis was affected by 6mT SMF exposure. Exposure of cells to SMF during 4h incubation with particles, increased, within the first two hours, the number of bound particles to the plasma membrane and decreased those internalized. At 4 hours of incubation with particles under SMF the number of particles bound to the plasma membrane decreased and increased the number of engulfed ones; the amount, surprisingly, being higher than in non exposed cells. The effects, due to the presence of SMF during the internalization of latex particles or apoptotic cells, were higher at the early stages of the induction to differentiation and in any case they increased the rate of internalization, specific for each cell type (THP1 > U937 cells).