MDSCs frequency in blood is correlated with clinical parameters in adult CAP patients.

(A)correlations between the frequencies of G-MDSCs and c-reactive protein (CRP) level in blood of 63 CAP patients.(B) correlations between the frequencies of G-MDSCs and neutrophil percentage in peripheral blood from 63 CAP patients. (C) correlations between the frequencies of M-MDSCs and neutrophil percentage in peripheral blood from 63 CAP patients. (D) correlations of the frequencies of M-MDSCs and CRP level in blood of 63 CAP patients.</p

The frequency of MDSCs subsets in peripheral blood of CAP patients.

(A)The gated strategies to identify M-MDSCs.(B)The gated strategies to identify G-MDSCs.(C)The percentage of M-MDSCs in the peripheral blood from 24 healthy controls and 63 CAP patients.(D) The percentage of G-MDSCs in the peripheral blood from 24 healthy controls and 63 CAP patients. ****p<0.0001.</p

Altered expression of PD-L1 and PD-L2 expression on MDSC subsets in peripheral blood of CAP patients.

(A)FACS analysis of surface expression of CD274 (PD-L1) on G-MDSCs in peripheral blood from 24 healthy controls and 63 adult CAP patients.(B) FACS analysis of surface expression of CD273 (PD-L2) on G-MDSCs in peripheral blood from 24 healthy controls and 63 adult CAP patients. (C)FACS analysis of surface expression of CD274 (PD-L1) on M-MDSCs in peripheral blood from 24 healthy controls and 63 adult CAP patients. (D)FACS analysis of surface expression of CD273 on M-MDSCs in peripheral blood fro m 24 healthy controls and 63 adult CAP patients.***p<0.001, ****p<0.0001.</p

Increased expression of PD-1 and CTLA-4 on Treg in CAP, without no significant difference in the frequency of Treg.

(A)The gated strategies to identify Tregs. (B)FACS analysis of Treg cells in peripheral blood from 24 healthy controls and 63 adult CAP patients. (C-D)FACS analysis of surface expression of PD-1 and CTLA-4 on Treg in peripheral blood from24 healthy controls and 63 adult CAP patients. (E-F)FACS analysis of surface expression of PD-1 and CTLA-4 on CD4+Tcells in peripheral blood from24 healthy controls and 63 adult CAP patients.(J-H)FACS analysis of surface expression of PD-1 and CTLA-4 on CD8+Tcells in peripheral blood from24 healthy controls and 63 adult CAP patients. *p<0.05.**p<0.01.</p

Characteristics of all subjects.

BackgroundMyeloid-derived suppressor cells (MDSCs) have been reported to expand and have a potent ability in the expansion of regulatory T cells in malignant and infectious disease. The current study was performed to investigate the role of MDSCs and possible immune mechanisms in dampening immune responses of community acquired pneumonia (CAP).MethodsThis was a single-center cross-sectional study. The distribution of MDSCs subsets, the PD-1/PD-L1(L2) level of MDSCs subsets and Tregs in the peripheral blood of adult CAP patients and healthy control were measured by flow cytometry analysis.ResultsPeripheral blood mononuclear cells (PBMCs) from 63 adult CAP patients contained an elevated frequency of both G-MDSC (4.92±0.30 vs 2.25±0.21,pConclusionsIn summary, the significant expansion of circulating MDSCs subsets and the up-regulated expression of PD-1/PD-L1 level in CAP patients may suggest the possible involvement of PD-1/PD-L1axis in MDSCs mediated immune regulation on Treg at least partially in CAP patients.</div