## 1 Introduction  
The influence of physical factors, and in particular of the magnetic fields, on living organisms has become an increasingly relevant biophysical topic in recent years. While studies addressing interactions between high-intensity magnetic field and matter have been awarded a number of Nobel Prizes, effects of weak and super weak magnetic fields have become the subject of research only recently. To most objectively elucidate the mechanisms underlying the biological action of weak and super weak combined (collinear static and alternating) magnetic fields (CMF), an experimental study of the effects associated with different CMF modes at a cellular level using well-studied standard models would be required. One of such models, previously shown to be sensitive to variations in the parameters of applied magnetic fields, is the neutrophil respiratory burst [1]. During phagocytosis and in response to soluble mediators (e.g., bacterial peptide N-formyl-Met-Leu-Phe (fMLF) or the phorbol ester phorbol 12-myristate 13-acetate (PMA)) neutrophils generate reactive oxygen species (ROS): hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)), superoxide anion radical (O\({}_{2}\)\({}^{-\bullet}\)), singlet oxygen (\({}^{1}\)O\({}_{2}\)), hydroxyl radical (OH\({}^{\bullet}\)), and nitric oxide (NO). These molecules are involved in the destruction of phagocytosed objects. One of the most sensitive techniques that detects ROS is based on the measuring of chemiluminescence generated upon oxidation of luminol (luminol-enhanced chemiluminescence) [2]. We have previously detected a priming effect (pre-activation of the neutrophil respiratory burst) occurring with exposure to a weak combined collinear static (42 \(\upmu\)T) and low-frequency alternating magnetic field (formed by a series of 1, 4.4 and 16.5 Hz sinusoidal signals with a total amplitude of 0.86 \(\upmu\)T). This priming effect produced by the magnetic fields was evidenced by more pronounced enhancement of chemiluminescence in neutrophil suspensions (following 60-min exposure to CMF) in response to the administration of fMLF or PMA [1]. When selecting the parameters of the alternating low-frequency component of CMF for the respiratory burst triggering, we relied on the results obtained previously for the effects of magnetic field with similar characteristics on mice with transplanted Ehrlich ascites carcinoma [3; 4; 5]. In that study, as the algorithm to generate the alternating magnetic signal, we used the principle of adjusting the magnetic field to ICR frequencies of simple and complex ions: (NAD)\({}^{+}\), the ionic form of glutamic acid and K\({}^{+}\) ions (1.0, 4.4 and 16.5 Hz, respectively for these ions, using a static magnetic field of 42 \(\upmu\)T) [2; 4; 5]. This combined triple-frequency signal had the most pronounced antitumor activity, as compared to each individual frequency [3; 4; 5]. When studying the molecular mechanism of the CMF activating effect on ROS production by neutrophils, we showed that it was less associated with lipid peroxidation. The lipid peroxidation inhibitor butyl hydroxytoluene (BHT) did not reduce the production of ROS [6]. However, the effect of CMF on calcium-dependent processes in neutrophils was confirmed using calcium chelator (BAPTA-AM), which dramatically reduced the CMF activating effect on ROS production [7]. Subsequent experiments demonstrated a relationship between pre-activation of the neutrophil respiratory burst by weak CMF and the concentration of atmospheric gases [8]. It was shown that preliminary mild partial deaeration of the neutrophil suspension at an atmospheric gas pressure of 640 mm Hg led to a substantial (4-fold) reduction in the response only when the CMF was applied. At the same time, the ability of the cells to generate the respiratory burst in response to a stimulus (fMLF) was nearly unchanged in the control assays, without the CMF applied [8].