Fig. 1

Immune characteristics are closely correlated with disease progression of COVID-19. a Lymphocyte subpopulations in the peripheral blood of COVID-19 (n = 36) and control (healthy donor, n = 36) groups were evaluated by flow cytometry. Cell numbers of total lymphocytes, total T, CD4⁺ T, CD8⁺ T, B, and NK cells were analyzed. Levels of cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ) in the peripheral blood of COVID-19 and control (healthy donor, n = 36) groups were evaluated by flow cytometry, presented as a histogram. b Kaplan–Meier survival curves for 36 severe and critical COVID-19 patients with high and low levels of lymphocyte subpopulations, IL-6 and IL-10. c CT imaging matched with lymphocyte subpopulations from one representative patient during disease recovery. Before: disease severe stage; After: disease recovery stage. d CT imaging matched with IL-6 and IL-10 levels from one non-survivor and one survivor. e (1,3)-β-D-glucan in patients with high and low levels of lymphocyte subpopulations was analyzed by G test. f Patient numbers with high and low lymphocyte subpopulations infected with microbiota. g The relationships between IL-6 and D-Dimer, AST, Urea, CK, and LDH, or IL-10 and γ-GT were analyzed. Data are represented as means ± standard error (SE). ns nonsignificant, *P < 0.05