Fig 3. Circulating levels of PF4, sP-selectin levels, and TPO were significantly elevated in COVID-19.

(A) PF4, (B) sP-selectin (sCD62P), and (C) TPO plasma levels from patients with severe (n = 6) and nonsevere (n = 6) COVID-19 compared to hospitalised (n = 6) and healthy (n = 6) controls were measured in triplicate by ELISA. Boxplots represent the data median (line inside the box) and the IQR (outline of the box) together with data maximum and data minimum (whiskers) and individual observations (see individual data in S1 Data). Statistical analysis was performed using a two-tailed t test, and p-values were adjusted for multiple comparisons using a Holm–Bonferroni post hoc test. COVID-19, Coronavirus Disease 2019; ELISA, enzyme-linked immunosorbent assay; IQR, interquartile range; PF4, platelet-factor 4; sP-selectin, soluble P-selectin; TPO, thrombopoietin.