Human Alveolar Macrophage Activation in Healthy Subjects and in COPD-Patients Evaluated by Magnetopneumography

Magnetopneumography (MPG) has been used to study long-term particle clearance of the human lungs in healthy and disease [1, 2]. Ferrimagnetic iron-oxide test particles are inhaled and used as a tracer. The particles have a sufficient stability in order to monitor alveolar clearance over a year without any burden to the subjects. Within hours after particle deposition they are phagocytized by alveolar macrophages (AM). This moves the particles to the intracellular environment, now being under the cellular motile activity. After magnetization the particles form small remanent magnets, all being oriented parallel to the external field. This allows to detect a small macroscopic lung field (LF). The LF decays within ≈20 minutes. Because of the remanent magnets the decay must be due to a stochastic rotation of the particles, finally leading to zero LF. It has been shown that this decay, called relaxation, reflects intracellular phagosome motion and thereby is a monitor for the motile activity of the AM-cells. In this study intracellular phagosome motion was investigated in healthy non-smokers (NS) and smokers (S) and in patients with chronic obstructive pulmonary disease (COPD), answering the question whether smoking might affect cellular motility. Further investigations have shown that relaxation can be influenced by inert particle exposure [3]. This study shows that an AM-activation was induced by the deposition of the magnetic test-particles, that depends on cigarette smoking. MPG provides a method to detect AM-activation in vivo without medical treatment, like a bronchoalveolar lavage (BAL).