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The immunological pathways that cause Multisystem Inflammatory Syndrome after SARS-CoV-2 infection in children (MIS-C) remain under investigation. The aim of this study was to prospectively compare the T-cell cytokine expression profile between children with convalescent COVID-19 or MIS-C. Peripheral blood mononuclear cells (PBMCs) were isolated from unvaccinated children with acute MIS-C (MIS-CA) before immunosuppression, convalescent MIS-C (one month after syndrome onset, MIS-CC), convalescent COVID-19 (one month after hospitalization) and healthy, unvaccinated controls. Intracellular expression of IL-4, IL-2, IL-17, IFN-γ, TNF-α and Granzyme B, post SARS-CoV-2-Spike antigenic mix stimulation of T cell subsets was analyzed by 13-colour Flow Cytometry. Twenty children (4 MIS-CA, 4 MIS-CC, 8 post-COVID-19, and 4 controls) with median age (IQR): 11. 5 (7. 25-14) years were included in the study. From the comparison of the flow cytometry analysis of the 14 markers of MIS-CA with the other 3 groups (MIS-CC, post-COVID-19 and controls), statistically significant differences were identified for: 1. CD4 +IL-17 +/million CD3 +: 293. 0 (256. 4-870. 9) vs 50. 7 (8. 4-140. 5) ; P-value: 0. 03, vs 96. 7 (89. 2-135. 4) ; P-value: 0. 03 and vs 8. 7 (0. 0-82. 4) ; P-value: 0. 03, respectively, 2. CD8 +IL-17 +/million CD3 +: 335. 2 (225. 8-429. 9) vs 78. 0 (31. 9-128. 9) vs 84. 1 (0. 0-204. 6) vs 33. 2 (0. 0-114. 6) ; P-value: 0. 05, respectively 3. CD8 +IFN-γ +/million CD3 +: 162. 2 (91. 6-273. 4) vs 41. 5 (0. 0-77. 4) ; P-value: 0. 03 vs 30. 3 (0. 0-92. 8) ; P-value: 0. 08, respectively. In children presenting with MIS-C one month after COVID-19 infection, T cells were found to be polarized towards IL-17 and IFN-γ production compared to those with uncomplicated convalescent COVID-19, a finding that could provide possible immunological biomarkers for MIS-C detection.
Filippatos et al. (2024) studied this question.