Analysis of leukogram parameters and blood cytokine profile in tick-borne infections of various etiologies

Abstract

Introduction. Studies aimed at identifying pathogenetic features of tick-borne natural focal infections depending on etiological agent are relevant to seek out for new associations of biomarkers characterizing the structural and functional phenotype of immune cells significant for the differential diagnosis and prognosis of diseases. The aim of the study was to evaluate the parameters of a leukogram with an expanded profile in relation to the parameters of cytokine status in patients with viral tick-borne encephalitis as well as erythemic tick-borne borreliosis at acute stage of the disease. Materials and methods. The study involved 28 patients with the non-erythemic tick-borne borreliosis and 27 patients with tick-borne encephalitis at the acute stage of the disease, as well as 16 healthy individuals (control group). Venous blood samples were examined using a Sysmex XN1000 analyzer based on reflex testing technology with extended profile allowing to characterize leukocyte reaction during infection and inflammation, including parameters such as the absolute and relative count of immature granulocytes (IG), neutrophil granularity index (NEUT-GI), neutrophil reactivity index (NEUT-RI), count of reactive lymphocytes (RE-LYMP), count of antibody-producing lymphocytes (AS-LYMP). Concentrationof IL-2, IL-4, IL-6, IL-8, IL-10, IFN and TNF in blood serum was determined by enzyme immunoassay using specific reagent kits (Vector-Best, Russia). Results. It was found that changes in the quantitative composition of blood leukocytes in patients with viral tick-borne encephalitis and non-erythemic form of tick-borne borreliosis have a unidirectional tendency characterized by increased count of metabolically active neutrophils (NEUT-RI) and a decreased count of reactive lymphocytes (RE-LYMP) compared to healthy individuals. Changes in the leukogram occur along with high blood concentration of proinflammatory cytokines IL-8 and TNF and a low level of IFN. A positive direct correlation was revealed between the fluorescence intensity parameter characterizing the metabolic activity of neutrophil granulocytes (NEUT-RI) and blood serum IL-8 level both in tick-borne encephalitis (r = 0.422, p 0.05) and non-erythemic form of tick-borne borreliosis (r = 0.551, p 0.05). Additionally, in the former, a positive correlation was established between the total leukocyte count (WBC) and concentration of TNF in the blood serum (r = 0.532, p 0.05).