The Ability of Blood Plasma to Inhibit Catalase in the Presence of Chloride is a Highly Sensitive Indicator of Deposited Nitric Oxide and Leukocyte Activation

Abstract

Aims: To find out the origin of so-called nitrite - like substance (NLS) that appears in the blood plasma in patients with inflammatory diseases and the mechanism of its occurrence. To justify the possibility of registering its appearance in the blood as a highly sensitive indicator of leukocyte activation. Background: The need for a simple, sensitive and specific method of early diagnosis of inflammation, the key stage of which is the activation of white blood cells. Objective: To find out the origin of so-called nitrite - like substance (NLS) that appears in the blood plasma in patients with inflammatory diseases before the onset of clinical signs. This substance is able to inhibit catalase in the presence of chloride which is typical for nitrite and nitrosoamines. Methods: The catalase activity was determined by the calorimetric method based on the control of the kinetics of heat production accompanying hydrogen peroxide decomposition. Results: Blood plasma contains deposited nitric oxide included in various nitrosyl iron complexes. These complexes effectively interact with the superoxide produced by activated leukocytes. This interaction produces a number of substances that have the ability to inhibit catalase in the presence of chloride. These substances retain the ability to inhibit in the system: hemoglobin-iron chelator, or hemoglobin-mercury salt. Such properties are characteristic of nitrite and nitrosoamines. Normally, these substances are present in plasma in trace amounts. 700 activated cells per microliter (10 times less than normal in human blood) are enough to transform about 30% nitrosyl iron complexes contained in plasma into NLS. Conclusion: The appearance of NLS is a very sensitive indicator of leukocyte activation.