Table 1.
Summary of current studies on MDSCs in COVID-19 patients.
| # | Study size (COVID-19 patients + Healthy donors (HD)) | Source of MDSC | Density gradient centrifugation | Fresh/cryopreserved samples | Markers of MDSCs | MDSC frequency | Functional assay in vitro | Reference |
|---|---|---|---|---|---|---|---|---|
| 1 | N = 180 (COVID-19: 19 mild, 58 moderate, 58 severe, 12 fatal; HD: 33) | Peripheral blood (PB), nasopharyngeal (NPA) and endotracheal (ETA)aspirates | Yes | Fresh | M-MDSC: Lin−HLA-DR−CD14+ PMN-MDSC: Lin−HLA-DR−CD66abce+LOX1+ |
Increase in M-MDSC and PMN-MDSC in PB (proportion, in COVID-19 patients as compared to HD, in severe patients as compared to mild and moderate patients) No change in M-MDSC and PMN-MDSC in NPA and ETA (proportion) |
Inhibition of antigen-nonspecific T cell proliferation and IFNγ production | [63] |
| 2 | N = 40 (COVID-19: 20 mild; HD: 20) | PB | No | Fresh | M-MDSC: CD11b+HLA-DR−CD33+ CD14+CD15− PMN-MDSC: CD11b+HLA-DR−CD33+CD14−CD15+ |
Increase in M-MDSC (counts, in COVID-19 patients as compared to HD) No change in PMN-MDSC (counts, in COVID-19 patients as compared to HD) |
None | [73] |
| 3 | N = 59 (COVID-19: 38 acute, 10 recovered; HD: 11) | PB | Yes | Cryopreserved | M-MDSC: Lin−HLA-DR−CD33+CD14+CD15− PMN-MDSC: CD15+CD16+LOX1+ |
Increase in M-MDSC and PMN-MDSC (proportion, in acute COVID-19 patients as compared to HD) | None | [65] |
| 4 |
N = 70 (COVID-19: 5 asymptomatic, 24 severe, 10 deceased, 26 convalescent; HD: 15) |
PB, lungs | Yes | Fresh | M-MDSC: HLA-DR-/dimCD14+ PMN-MDSC: CD66b+HLA-DR−CD14− |
Increase in M-MDSC and PMN-MDSC in PB (proportion, in severe patients as compared to convalescent, asymptomatic and HD) PMN-MDSC infiltrates in the lungs |
None | [64] |
| 5 | N = 158 (COVID-19: 32 non-ICU, 96 ICU; HD: 30) | PB | Yes | Fresh | PMN-MDSC: Lin−HLA-DR−CD11b+CD33+CD15+CD14− | Increase in PMN-MDSC (proportion, in COVID-19 patients as compared to HD, in ICU patients as compared to non-ICU) | Inhibition of antigen-nonspecific proliferation and antigen-specific IFNγ production by T cells | [71] |
| 6 |
N = 68 (COVID-19: 41 non-ICU; 7 ICU; HD: 20) |
PB | Yes | Fresh | Customized Duraclon tubes | Increase in MDSC (proportion, in COVID-19 patients as compared to HD) | None | [85] |
| 7 | N = 26 (COVID-19: 9 mild, 9 severe; HD: 8) | PB | Yes | Fresh | PMN-MDSC: Lin−HLA-DRdim/−CD11b+CD33+CD15+CD14− | Increase in PMN-MDSC (proportion, in COVID-19 patients as compared to HD, in severe patients as compared to mild patients) | Inhibition of antigen-nonspecific T cell proliferation and IFNγ and TNFα production |
[67] |
| 8 | N = 39 (COVID-19: 13 moderate, 13 severe; HD: 13) | PB | Yes | Fresh | M-MDSC: HLA-DRdimCD14+; PMN-MDSC: Lin−HLA-DRdimCD16+CD15+ e-MDSC: Lin−HLA-DRdimCD33+CD15+ |
Increase in M-MDSC and PMN-MDSC (count, in COVID-19 patients as compared to HD, in severe patients as compared to moderate patients) | No | [75] |
| 9 | N = 57 (COVID-19: 21 mild, 20 severe; HD: 16) | PB | Yes | Fresh | M-MDSC: Lin−HLA-DRdim CD11b+CD14+; PMN-MDSC: Lin−HLA-DRdimCD11b+CD15/CD66b+ e-MDSC: Lin−HLA-DRdimCD66b/CD15−CD14− |
Increase in M-MDSC and PMN-MDSC (proportion and count, in severe COVID-19 patients as compared to HD and mild patients) | Inhibition of antigen-nonspecific T cell proliferation | [76] |
| 10 | N = 47 (COVID-19: 12 mild,15 moderate, 13 severe; HD: 7) | PB | Yes | Cryopreserved | M-MDSC: Lin−HLA-DR−CD11b+CD33+CD14+CD15−; PMN-MDSC: Lin−HLA-DR−CD11b+CD33+CD14−CD15+ e-MDSC: Lin−HLA-DR−CD11b+CD33+CD14−CD15− |
Increase in PMN-MDSC (proportion, in severe discharged patients as compared to HD, mild, moderate, and severe deceased patients). No change in M-MDSc and e-MDSC (proportion, in patients as compared to HD) |
No | [72] |
| 11 | N = 61 (COVID-19: 39 ICU; HD: 22) | PB | No | Fresh | PMN-MDSC: CRTH2− CD15+LOX-1+CD10dimCD16dim | Increase in PMN-MDSC (proportion, in ICU patients as compared to HD) | Inhibition of antigen-nonspecific T cell production of IFN-g |
[66] |
| 12 | N = 27 (COVID-19: 19 non-ICU; 8 ICU; HD: 11) | PB | No | Fresh | M-MDSC: HLA-DR-/dimCD14+ | Increase in M-MDSC (proportion, in ICU patients as compared to non-ICU and HD, in non-ICU as compared to HD) | No | [86] |
| 13 | N = 57 (COVID-19: 21 mild, 15 severe, 9 convalescent; HD: 12) | PB | Yes | Fresh | M-MDSC: Lin−HLA-DR-/dimCD11b+CD33+CD14+CD15− PMN-MDSC: Lin−HLA-DR-/dimCD11b+CD33+CD14−CD15+ e-MDSC: Lin−HLA-DR−CD11b+CD33+CD14−CD15− |
Increase in M-MDSC and PMN-MDSC (proportion, in severe patients as compared to mild, convalescent patients and HD). No change in e-MDSC (proportion) |
No | [2] |
| 14 | N = 58 (COVID-19: 13 moderate, 37 severe; HD: 8) | PB | No | Fresh | M-MDSC: HLA-DR-/dimCD11b+CD14+CD15− PMN-MDSC: HLA-DR-/dimCD11b+CD14−CD15+ |
Increase in M-MDSC and PMN-MDSC (proportion, in patients as compared to HD) | No | [84] |
| 15 | N = 26 (COVID-19: 13 convalescent; HD: 13) | PB | Yes | Fresh | M-MDSC: Lin−HLA-DR-/dimCD11b+CD14+CD15− PMN-MDSC: Lin−HLA-DR-/dimCD11b+CD14−CD15+ e-MDSC: Lin−HLA-DR−CD11b+ CD14−CD15− |
Increase in PMN-MDSC (proportion, in convalescent patients as compared to HD). No change in M-MDSC and e-MDSC (proportion) |
Inhibition of antigen-nonspecific T cell proliferation | [68] |
| 16 | N = 67 (COVID-19: 26 mild, 15 severe; HD: 26) | PB | Yes | Fresh | M-MDSC: HLA-DR−CD11b+CD66b−CD14+CD15− PMN-MDSC: HLA-DR−CD11b+CD66b+CD14−CD15+ |
Increase in M-MDSC and PMN-MDSC (proportion, in patients as compared to HD; increase in PMN-MDSC in mild patients as compared to severe patients) | No | [70] |
| 17 | N = 120 (COVID-19: 27 mild, 47 severe, 46 deceased) | PB | No | Fresh | M-MDSC: HLA-DR−CD14+ |
Increase in M-MDSC (proportion, in deceased patients as compared to mild and severe patients) | No | [3] |
| 18 | N = 80 (COVID-19: 40 ICU discharged, 40 ICU deceased) | PB | No | Fresh | M-MDSC: HLA-DR-/dimCD11b+CD33+CD14+CD15− PMN-MDSC: HLA-DR-/dimCD11b+CD33+CD14−CD15+ |
Increase in PMN-MDSC (counts, in ICU deceased patients as compared to ICU discharged) | No | [103] |
| 19 | N = 20 (COVID-19: 11 non-ICU, 9 ICU) | PB | Yes | Cryopreserved | M-MDSC: Lin−HLA-DR−CD11b+CD33+CD14+CD15− PMN-MDSC: Lin−HLA-DR−CD11b+CD33+CD14−CD15+ |
Increase in total MDSC (proportion, in ICU patients as compared to non-ICU) | No | [105] |