One Virus, Two Diseases: Evaluation of Clinical and Immunological Differences in Covid-19 and Multisystem Inflammatory Syndrome Cases.

Objectives: This study aims to uncover early detection markers through the immunological analysis of children diagnosed with multisystem inflammatory syndrome (MIS-C) and coronavirus disease-2019 (COVID-19).

Methods: We retrospectively analyzed immunological data from thirty-three MIS-C patients and an equivalent number of patients under the age of 18 with a positive polymerase chain reaction (PCR) test for COVID-19. These individuals were admitted to Ondokuz Mayis University between November 2020 and February 2021. In total, the study group consisted of 66 patients and an additional 10 healthy controls.

Results: Lymphopenia, thrombocytopenia, anemia, and neutrophilia, along with elevated levels of ferritin, D-dimer, and C-reactive protein, were more pronounced in MIS-C patients (p<0.001). No significant disparities were found in serum IgG, A, M, and E concentrations. Notably, there was an increased proportion of B cells (p<0.001), an inversion of the CD4/CD8 ratio, and a marked presence of CD3+CD38+HLA-DR+active T cells (p=0.009) in the MIS-C cohort.

Conclusion: In the early diagnosis of MIS-C, lymphopenia, increase in B cells, reversal of CD4/CD8 ratio, and demonstration of CD3+CD38+HLA-DR+active T cells may be helpful.