Markers of systemic leukocyte activation for assessing acute and chronic systemic inflammation

The phenomenon of systemic leukocyte activation is a component of systemic inflammation (SI), known as the systemic inflammatory response (SIR). Currently, there are hundreds of molecular markers that can serve as criteria for systemic activation, including soluble receptor to IL-2 (sIL-2R) or CD25, β2-microglobulin, and eosinophil cationic protein (ECP). The objective of our study was to assess whether markers of systemic leukocyte activation can be used as criteria for acute and chronic systemic inflammation. Data from 121 patients with acute critical infectious conditions – intensive care patients with sepsis-2 (according to the 2001 consensus, without MODS) and sepsis-3 (2016 consensus, with MODS) – and 136 patients with non-infectious genesis (polytrauma with and without MODS) were analyzed to study acute SI. Additionally, data from 148 patients with immune-inflammatory rheumatic diseases were analyzed to study chronic SI. The reactivity level (RL) was calculated using the author’s method to assess the intensity of SIR. The development of SI was verified based on the measured concentrations of IL-6, IL-8, IL-10, TNFα, CRP, D-dimers, cortisol, myoglobin, and troponin I. Criteria for leukocyte activation phenomenon were sIL-2R > 700 units/mL, β2-microglobulin > 3000 ng/mL, and ECP > 10 ng/mL.

Based on the study results, TNFα, ECP, and β2-microglobulin were identified as the most stable indices for dividing groups with and without systemic vasculitis in both acute and chronic diseases. These indices indicate the typical character of systemic leukocyte activation and can be used to assess the intensity of the described phenomenon when integrated into the SI score. However, it is doubtful that these indices can be independently applied as criteria for the complex process of SI and even the SIR phenomenon. This is because the registration of threshold values for two criteria simultaneously during the acute process of SI was only observed in 40.2% of cases, and in chronic processes, it was only observed in 23.7%. These values were comparable to the group without acute SI. Additionally, all three additional criteria were only determined in acute SI in 20.5% of cases and in chronic SI in 3.4%.