Laboratory blood markers in COVID-19 and their connection to Viral variant

Abstract

Morality rates in COVID-19 are dependent on timely diagnosis. Therefore, studying the relationship between laboratory markers and the severity of disease is important. The first wave of COVID-19 associated with the spread of the original strain of SARS-CoV-2, showed higher mortality rates caused by cytokine storm. As the viral variant changed, a change in the disease course towards a less pronounced inflammatory reaction was observed. These changes affected major players of inflammation, cytokines. However, cytokines are not the only markers in the inflammatory response. The purpose of this work was to determine the significance of laboratory markers in inflammation: WBC, C-reactive protein, ferritin, fibrinogen, and D-dimer. The study included 227 patients with acute COVID-19 in the first 5–7 days from the onset of the disease from January 2021 to March 2022. When compared with reference, all groups were characterized by reduced absolute values of lymphocytes. Correlation analysis between the absolute value of lymphocytes and plasma cytokine concentrations also revealed statistically significant strong relationships with the level of the chemokine CCL22/MDC. Given that CCL22/MDC is an important component of lymphopoiesis, its low concentrations may indicate dysregulation of this process in COVID-19. In addition, we noted a positive correlation between the level of C-reactive protein and IL-6 in peripheral blood. IL-6 is a proinflammatory cytokine, and its elevated levels have been associated with the development of severe COVID-19. One of its functions is the induction of C-reactive protein, and this trend persists regardless of which variant causes COVID-19. We also noted positive correlations between the concentrations of fibrinogen and IL-18, ferritin and IL-6, IL-18. Both of these proteins are involved in inflammation along with cytokines. The literature provides data on the significance of these markers for determining the severity of COVID-19. There is evidence of a synergistic effect of ferritin and IL-18 against viral pathogens. Of interest was the negative correlation between plasma D-dimer levels and IFNα. At the same time, data on the role of the latter in thrombus formation processes are increasingly appearing in the literature.