Recognition and engulfment of the apoptotic cells: influence of the environment

Phagocytosis of apoptotic cells is the last, but very important step of the apoptotic program. The removal of apoptotic cell is mediated by specific epitopes, externalized progressively during the apoptotic program on the dead cells and by specific receptors on the phagocytes. Phagocytosis requires distinguishing features on the surface of apoptotic cells, recognition and tethering molecules, as well as the cytoskeletal and other cellular machinery involved in engulfment. If the details of the interaction between apoptotic cells and phagocytes are still far to be fully understood, even more obscure are the external and/or physiological factors able to modulate the process of phagocytosis of apoptotic cells. It is likely that any factors influencing cell surface molecules expression (on phagocyte and /or apoptotic cells) can in turn affect recognition of apoptotic cells. We have hypothesized that one of the possible candidate as external perturbting factor is the (E)MF exposure, in consideration of the reports indicating plasma membrane as the primary site for the (E)MF bioeffects. While the number of machine and electronic device are increasing also in the medical practice, numerous evidences are indicating biological effects of EMF (electromagnetic field) and MF (magnetic field), static as well as oscillating. Therefore, we studied the recognition of apoptotic lymphocytes by liver sinusoidal cells under exposure to 6 mT static magnetic field to define at which extent static magnetic fields are able to modulate this specific type of phagocytosis. Taking into account, that the physiological conditions and/or the developmental story of the cells affect the response to the static MFs exposure, in our study we investigated also the effect of the age to the exposure to static MF and their removal from liver circulation. We found that the recognition of apoptotic lymphocytes by the sinusoidal liver cells is affected by environmental stress, like exposure to static MF, as well as by the metabolic state, i.e. age of the cells to be removed. In particular, the exposure to static MF has been found to be an extremely critical factor for the recognition of not only apoptotic lymphocytes, but especially for control ones.