Fig. 3: Compositional changes and CD55 expression in monocytes subpopulation.

A UMAP representation of 19,303 monocytes coloured by cell type and B cluster assignment, as indicated on the figure. C UMAP representation of all the monocytes analysed across different disease states as indicated (healthy group: 3060 cells, mild disease group: 5750 cells, severe disease group: 2289 cells and critical disease group: 8204 cells). D Stacked bar plot representing monocyte cluster quantitative changes (%) in each disease state as indicated. E Pearson correlation plot of scaled expression values followed by hierarchical clustering, for the most variable genes identified in the monocytes subpopulations integrated. Colour spectrum represents positive correlations in red, to no correlation in white, to negative correlation in blue. F scRNA-seq heatmap showing the average scaled expression for selected marker genes of each subpopulation; mean expression is colour coded as indicated. G Feature plots showing CD55 gene expression in the monocytes subpopulation UMAP space. H Dot plot depicting expression levels of CD55 in all monocytes clusters across disease state; the dot size represents the fraction of cells in the clusters, mean expression is colour coded as indicated. I CD55 expression levels in each monocyte cluster, in healthy and severe donors as indicated. Mean expression bar plots, with error bars representing the 95% bootstrapped confidence intervals around the mean. Statistical analysis performed by the Wilcoxon rank sum test *p < 0.05, **p < 0.01, ****p < 0.0001. J Side-by-side plots of flow cytometry histograms showing CD55 expression in monocytes; severe disease patient sample (blue histogram), critical disease patient sample (red histogram) and healthy control sample (grey histogram). K Bar plots depicting quantitation of CD55 protein expression levels in monocytes determined by flow cytometric analysis in severe (n = 20) and critical (n = 20) COVID-19 patient cohorts (mean ± SD); Statistical analysis was performed by one-way ANOVA testing for more than two groups comparisons. Post-hoc analysis was performed by Fisher’s least significant difference test. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.