Fig. 4: CD16+ NK cells and monocytes of acute MIS-C patients have increased cell surface levels of IL-18R and CD95.

Monocyte and NK cell populations were analysed in (A–K) in the same experiment groups shown in Fig. 3: acute MIS-C (n = 17), MIS-C follow-up (n = 7), PICU COVID-19 pneumonia (n = 10) or acute paediatric infection (n = 14, mixed chest, gastrointestinal and systemic infections). Frequency in PBMCs of A total NK cells or B CD16+ NK cells and median metal staining intensity of C CD95 or D IL-18R on CD16+ NK cells. E–G show the proportion of each subject’s monocytes classified into the three canonical subsets: classical (CD14++ CD16−), intermediate (CD14+ CD16+), or non-classical (CD14+ CD16++) monocytes. H–O show the MFI of the indicated proteins on the surface of classical monocytes using data from the T cell (H–K) or monocyte (L–O) CyTOF antibody panels (healthy children (n = 7), acute MIS-C (n = 13), MIS-C follow-up (n = 6), acute paediatric COVID-19 pneumonia (n = 9) or acute paediatric infection patients (n = 12, mixed chest, gastrointestinal and systemic infections)). Horizontal line indicates the median value of each group tested. Statistical testing was performed using ordinary one-way ANOVA; results of Dunnett’s multiple comparisons test comparing the acute MIS-C group to all other groups is shown in (A–D, K) and comparing healthy children to all other groups in (H–J, L–O). P Receiver operating characteristic curves of the indicated markers on particular cell subsets for MIS-C diagnosis (n = 17, acute samples) with infection samples as control (n = 14). Area under the curve values are shown in each graph. All four marker/cell combinations were significantly different between the two groups. Q Correlation between plasma IL-18 levels and frequency of the indicated cell populations. Pearson correlation coefficient and significance are shown on each graph. N = 9. Source data are provided as a Source Data file.