Features of laboratory parameters in children with multisystem inflammatory syndrome associated with SARS-CoV-2

Abstract

Multisystem inflammatory syndrome (MIS-C) is a new childhood disease associated with coronavirus SARS-CoV-2 that manifests itself 3–4 weeks after infection. The development of MIS-C is possible, despite the asymptomatic course of coronavirus infection. The pathogenetic features of MIS-C remain unclear. The aim of the study was to investigate the state of peripheral blood parameters in children with multisystem inflammatory syndrome associated with SARS-CoV-2 upon admission to a hospital. Material and methods. We examined 52 children with MIS-C from 1 to 14 years old, hospitalized in Children`s Clinical Hospital No. 3 in Novosibirsk in October–December 2020. Testing for the isolation of SARS-CoV-2 RNA in scrapings from the nasopharynx and oropharynx was carried out using real time PCR (test systems of DNA-Technology, Russia). The presence of specific IgM and IgG antibodies to SARS-CoV-2 in blood serum was determined by ELISA using Vector-Best kits (Russia). Results and discussion. It was noted that SARS-CoV-2 virus RNA was found only in 12.8 % of cases, while specific IgG antibodies in blood serum were detected in 100 % of children. IgM to SARS-CoV-2 antigens were detected in the blood serum only in 53.85 % of children with MIS-C. It has been established that unexpressed leukocytosis was found both in children under the age of 7 and in children of 8–14 years old. However, the leukocytes content in children of the older age group was significantly lower than in children aged 1–7 years. At the same time, in both age groups, some children had extremely low values of the indicator. The causes of severe leukopenia against the background of excessive inflammation remain unclear. Age groups (1–7 and 8–14 years) do not differ statistically significantly in the relative content of lymphocytes and neutrophils. In the study of individual values of the relative content of lymphocytes within the age groups, it was noted that only some children had lymphopenia of varying severity. Conclusions. Against the background of minor leukocytosis in children with MIS-C, upon admission to the hospital, there is a tendency to develop both relative and absolute lymphopenia, regardless of age. The study noted an extremely pronounced variability of individual values of the evaluated peripheral blood parameters, regardless of age, which, with similar clinical symptoms, characterized as MIS-C, requires further study in dynamics, taking into account the initial values of the indicators.There is no pronounced relationship between the leukocytes content and specific IgM antibodies to SARS-CoV-2 antigens in the blood.