Figure 2.

(A) Blood WBC, leukocyte populations, and T–cell subset count in peripheral blood of COVID–19 convalescents with normal range marked in green. Normal range for DNTs was calculated from T cells [1%–5% of T cells, (38)] (n = 13). (B) CD4⁺ and CD8⁺ T–cell distribution in individual patients. Patients with CD4⁺/CD8⁺ ratio above the normal range are marked in red, within the norm in green, and below the norm in blue (n = 13). (C) PD–1 expression on CD8⁺ T cells of COVID–19 convalescents. Expression of PD–1 on CD8⁺ T cells of COVID–19 convalescent and healthy controls was evaluated by flow cytometry and presented as mean fluorescent intensity (MFI). Data from four subjects in each group are presented (n = 4). (D) Correlation of the level of LDNs/PMN–MDSCs and the count of CD8⁺ in blood of COVID–19 convalescents. CD8⁺ T cells were identified by flow cytometry as CD45⁺CD3⁺CD8⁺ cells and their concentrations were calculated from the total lymphocyte counts (n = 13). (E) Correlation of the level of LDNs/PMN–MDSCs and the count of double–negative T cells (DNT) in blood of COVID–19 convalescents. Double–negative T cells (DNTs) were identified by flow cytometry as CD45⁺CD3⁺CD4^–CD8^– and their concentrations were calculated from the total lymphocyte counts (n = 13). (F) Correlation of CD4⁺/CD8⁺ T cell ratio with neutrophil count in blood of COVID–19 convalescents (n = 13). (G) Correlation of anti SARS– CoV–2 S1 IgG antibody concentration with the number of neutrophils in COVID–19 convalescents (n = 10). (H) Correlation of anti–SARS CoV–2 S1 IgG antibody concentration with the frequency of LDNs/PMN–MDSCs in COVID–19 convalescents (n = 10).