Modification of the Method for Determining Myeloperoxidase in Blood Neutrophils
Myeloperoxidase is a heme-containing peroxidase expressed primarily in neutrophils and to a lesser extent in monocytes. Determining the activity of myeloperoxidase in blood cells is one of the tests of the immune status of animals. Conventional methods are based on the oxidation of benzidine by the peroxide system to the unstable benzidine blue, which spontaneously turns into stable brown benzidine. The aim of this study was to develop a modification of the cytological determination of the myeloperoxidase enzyme using metol. The relative percentage of peroxidase-positive neutrophils in the peripheral blood of animals was determined after 100 neutrophils had been counted. The task was achieved by using the reaction with metol in the method of cytological determination of the activity of neutrophil myeloperoxidase in animal blood smears, which was based on the oxidation of metol by a peroxide system. Images of micropreparations were digitized using a Sony device for processing the received images of the cells. The Image Tool computer program was used for this purpose. The biological substrate was processed from a buffer-incubation mixture with subsequent drying and microscopy. The main new modification of the method was using metol. Metol does not have the ability to inhibit the activity of myeloperoxidase. The research showed easy and fast results. This method is economical and perspective for using in practice.
Keywords: myeloperoxidase, blood, neutrophils, metol
 Aratani, Y. (2018). Myeloperoxidase: Its Role for Host Defense, Inflammation, and Neutrophil Function. Journal Archives of Biochemistry and Biophysics vol. 64, pp. 47–52.
 Mandelkorn, J., et al. (1980). Immunofluorescent Demonstration of Myeloperoxidase of Phi Bodies and Rods in Leukaemic Leucocytes. Journal of Histochemistry and Cytochemistry ., vol. 12, pp. 449–456.
 Kettle, A. and Winterbourn, C. (1997). Myeloperoxidase: A Key Regulator of Neutrophil Oxidant Production Journal.Redox Report. vol. 3, issue 1, pp. 3–15.
 Ndrepepa, G. (2019). Myeloperoxidase - A Bridge Linking Inflammation and Oxidative Stress with Cardiovascular Disease. Journal Clinica Chimica Acta. vol. 493, pp. 36–51.
 Schultz, J. and Kaminker, K. (1962). Myeloperoxidase of the Leucocyte of Normal Human Blood. I. Content and Localization.Journal Archives of Biochemistry and Biophysics, vol. 96, pp. 465–467.
 Hampton, M., Kettle, A. and Winterbourn, C. (1998). Inside the Neutrophil Phagosome: Oxidants, Myeloperoxidase, and Bacterial Killing. Blood. vol. 92, issue 9, pp. 3007–3017.
 Blair-Johnson. M., Fiedler. T. and Fenna, R. (2009). Human Myeloperoxidase: Structure of a Cyanide Complex and its Interaction with Bromide and Thiocyanate Substrates. Biochemistry Journal, vol. 40, pp. 13990–13997.
 Klebanoff, S. and Hamon, C. (1972). Role of Myeloperoxidase-Mediated Antimicrobial Systems in Intact Leukocytes. Journal of the Reticuloendothelial Society, vol. 12, issue 2, pp. 170–196.
 Hirche, T., et al. (2005). Myeloperoxidase Plays Critical Roles in Killing Klebsiella Pneumoniae and Inactivating Neutrophil Elastase: Effects on Host Defense Journal of Immunology. vol. 174, issue 3, pp. 1557–1565.
 Aratani, Y., et al. (2006). Contribution of the Myeloperoxidase-Dependent Oxidative System to Host Defense against Cryptococcus Neoformans. Journal of Medical Microbiology, vol. 55, issue 9, pp. 1291–1299.
 Klebanoff, S., et al. (2013). Myeloperoxidase: A Front-Line Defender against Phagocytosed Microorganisms.Journal of Leukocyte Biology, vol. 93, pp. 185–198.
 Theilgaard−Mönch, K., Porse, B. and Borregaard, N. (2006). Systems Biology of Neutrophil Differentiation and Immune Response.Journal Current Opinion in Immunology, vol. 18, pp. 54–60.
 Dri, P., et al. (1982). New Approaches to the Detection of Myeloperoxidase Deficiency. Blood, vol. 60, pp. 323–327.
 Kitahara, M., Simonian, Y. and Eyre, H. (1979). Neutrophil Myeloperoxidase: A Simple, Reproducible Technique to Determine Activity.Journal of Laboratory and Clinical Medicine., vol. 93, issue 2, pp. 232–237.
 Graham, R. and Karnovsky, M. (1966). The Early Stages of Absorption of Injected Horseradish Peroxidase in the Proximal Tubules of Mouse Kidney: Ultrastructural Cytochemical Studies using Peroxidases as Protein Tracers.Journal of Experimental Medicine., vol. 124, pp. 1123–1133.