The
cytokine storm and
lymphopenia are reported in
coronavirus disease 2019 (COVID-19). Myeloid-derived suppressive cells (MDSCs) exist in two different forms, granulocyte (G-MDSCs) and monocytic (M-MDSCs), that both suppress T-cell function. In
COVID-19, the role of
chemokines such as
interleukin (IL)-8 in recruiting MDSCs is unclear. A recent report has correlated
IL-8 and MDSCs with poor clinical outcomes in
melanoma patients. In the current study, we evaluated the frequency of MDSCs and their correlation with serum
IL-8 levels in severe
COVID-19 patients from Iran. Thirty-seven severe patients (8 on ventilation, 29 without ventilation), thirteen moderate
COVID-19 patients, and eight healthy subjects participated in this study between 10th April 2020 and 9th March 2021. Clinical and biochemical features, serum, and whole blood were obtained. CD14, CD15, CD11b, and
HLA-DR expression on MDSCs was measured by flow cytometry.
COVID-19 patients compared to healthy subjects had a greater frequency of M-MDSCs (12.7±13.3% vs 0.19±0.20%,), G-MDSCs (15.8±12.6% vs 0.35±0.40%,) and total-MDSCs (27.5±17.3% vs 0.55±0.41%,). M-MDSC (16.8±15.8% vs 5.4±4.8%,) and total-MDSC (33.3±18.5% vs 17.3±13.3%) frequency was higher in non- ventilated compared to moderate
COVID-19 subjects. Serum
IL-8 levels were higher in patients with
COVID-19 than in normal healthy subjects (6.4±7.8 vs. 0.10±00 pg/mL). Ventilated patients (15.7±6.7 pg/mL), non-ventilated patients (5.7±2.7 pg/mL) and moderate patients (2.8±3.0 pg/mL) had significantly different levels of
IL-8. A negative correlation was found between the frequency of G-MDSCs and the international normalized ratio (INR) test (r=-0.39), and between the frequency of total-MDSCs and oxygen saturation (%) (r=-0.39).
COVID-19 patients with severe non-ventilated disease had the highest levels of M-MDSCs. In addition to systemic MDSCs, lung, serum
IL-8, and other inflammatory
biomarkers should be measured.