A short-term incubation of healthy donor lymphocytes with adenosine or adenosine diphosphoric acid was shown to reduce the number of cells expressing CD4 antigen and to increase the number of CD8 § lymphocytes. The hydra peptide morphogen shifts the balance of immunoregulatory lymphocytes toward a predominance of CD4 + cells. A hypothesis of a two-level system for the regulation of surface antigen expression by lymphocytes during exposure to extreme factors is proposed.

No abstract

Post-COVID syndrome is characterized by fatigue, reduced exercise tolerance, muscle and joint pain, and psychoemotional disorders. In the development of a generalized body response in a viral infection, abnormal defense responses are of great importance. We studied neutrophils, neutrophil extracellular traps (NETs), DNA degradation products (purine nitrogenous bases, PNBs), and traditional biochemical parameters.Aim. To determine biochemical parameters and the number of NETs and PNBs in the peripheral blood of patients with post-COVID syndrome.Materials and methods. The study included outpatients (n = 21) aged 18–59 years (36 [27 ÷ 50]). The control group consisted of 20 individuals aged 18–59 years (38.5 [29 ÷ 51.5]) without a past medical history of the coronavirus infection. All patients underwent a physical examination, their medical history was assessed, and the level of NETs and PNBs in the venous blood was determined.Results. 11 patients had a mild form of the disease in their past medical history, 7 – moderate, and 3 – severe. The most common symptoms in the patients were fatigue, headache, epigastric pain, dizziness, and joint pain. Hair loss and dyspnea were less common. The concentration of NETs and PNBs was higher in the patients with post-COVID syndrome than in the control group (p < 0.05). We detected NETs in the patients with post-COVID syndrome only in the form of filamentous structures. The concentration of extracellular purine bases in the blood of the patients with post-COVID syndrome was the highest in patients with moderate and severe acute periods. In patients with a mild acute period, the concentration of PNBs was 7.38 [0.0 ÷ 60.7] mg / ml, and in patients with moderate and severe acute periods – 19.15 [0.0 ÷ 33.5] and 34.19 [3.35 ÷ 70.0] mg / ml, respectively.Conclusion. Extracellular purine bases in concentrations capable of causing secondary alteration of cells are found in the peripheral blood of patients with post-COVID syndrome. Post-COVID syndrome is accompanied by the formation of filamentous NETs in the blood of patients.

Tissue damage in various diseases, hypoxic conditions, and some pathologies are associated with production of endogenous factors such as the soluble form of the surface receptor CD100, malonic dialdehyde, and arginase and their release into circulation. These factors modulate functional state of lymphocytes in the immune system: potentiate activation of B lymphocytes, activate synthesis and secretion of IL-25 and IL-17 cytokines, and suppress proliferative activity of T lymphocytes, thus modulating immunological reactivity of the organism. Reactions of innate and adaptive immunity develop against the background of changed immunological reactivity, which should be taken into account in the development of pathogenetically substantiated therapy.