Characteristics of bactericidal activity of healthy donors' peripheral blood against Escherichia coli

Abstract

Recently, the role of opportunistic pathogenic microorganisms in the development of inflammatory diseases of various localization has been relatively widely discussed. It is known that Escherichia coli are the etiological agent of such diseases, especially extraintestinal localization, a distinctive feature of which is considered to be a wide range of clinical manifestations. The aim of investigation was to assess the contribution of some components to the total microbicidal activity of healthy donors peripheral blood. Materials and methods. The bactericidal capacity of peripheral blood was assessed by the number of viable E. coli after incubation with blood samples by plating on Endo medium. The antibiofilm activity of whole blood and blood plasma was assessed by direct contact with the biofilm and its subsequent visualization using O'Toole technique. Phagocytic activity of neutrophils and monocytes was assessed separately in a microscopic version of the test. The production of reactive oxygen species was assessed using the stimulated and spontaneous luminol-dependent chemiluminescence reaction. An immunoglobulin G was used to opsonize E. coli. Results and discussion. It was shown that the peripheral blood of healthy volunteers has pronounced bactericidal properties against E. coli, reducing the number of viable bacteria by 2 times. Opsonization of E. coli reduces the number of bacteria by 4 times. Among leukocytes, the predominant place is occupied by neutrophils, which activate their absorption capacity and production of radicals faster than monocytes. The number of actively phagocytic neutrophils after E. coli treatment with an immunoglobulin G increased to 4.1±1.0% (without opsonization - 1.7±0.3%; p<0.05). Conclusion. In general, the microbicidal activity of the blood of healthy people is a multi-component system, in which a special place should be given to the factors of opsonization.