Figure 4.

Hallmarks of COVID-19 Compared to IAV (Revealed by Single-Cell Analysis of Cytokines, Cytokine Receptors, and Transcription Factors)

(A) The relative expression level (Z score) of key cytokines, cytokine receptors, and transcription factors among COVID-19 patients, IAV patients, and healthy controls in the activated CD4⁺ T cells population.

(B) The expression level of four representative genes highly expressed in activated CD4⁺ T cells of IAV patients. Upper panel: the color of each dot in the dot plot indicates expression level of the gene; dot size represents the fraction of cells expressing the gene in activated CD4⁺ T cells population. Lower panel: difference in gene expression among samples from COVID-19 patients (COV) (n = 16), IAV patients (IAV) (n = 4), and healthy donors (Ctrl) (n = 3). Each dot in the boxplot represents the average expression level of a gene in the activated CD4⁺ T cells population in one sample. Student’s t test was applied to test the significance of the difference. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001.

(C) Similar to (B), showing four representative genes highly expressed in the activated CD4⁺ T cells of COVID-19 patients.

See also Figure S4.