The Comparison of Monocyte Human Leukocyte Antigen-D-Related (mHLA-DR) Expression Levels Between Corona Virus Disease 2019 (COVID-19) Patients and Healthy Subjects.

BACKGROUND: SARS-CoV-2 can trigger a dysfunctional immune response in COVID-19 patients and lead to immunosuppression. HLA-DR molecule expressed on the surface of monocytes, known as mHLA-DR, has been widely used as a reliable marker of immunosuppression. Downregulation of mHLA-DR reflects an immunosuppressed state. This study aimed to compare the expression level of mHLA-DR between COVID-19 patients and healthy subjects concerning immune system dysregulation that can be triggered by SARS-CoV-2 and lead to immunosuppression. METHODS: This was an analytic observational study with a cross-sectional design that measured the mHLA-DR expression in EDTA blood samples from 34 COVID-19 patients and 15 healthy subjects using the BD FACSLyricTM Flow Cytometry System. The mHLA-DR examination results were expressed in AB/C (antibodies bound per cell) that were quantified using a standard curve constructed with Quantibrite phycoerythrin beads (BD Biosciences). RESULTS: Expression of mHLA-DR in COVID-19 patients (n = 34) were 21,201 [2,646-92,384] AB/C, with 40,543.5 [9,797-92,384] AB/C mild cases (n = 22), 21,201 [9,831-31,930] AB/C moderate cases (n = 6), and 7,496 [2,646-13,674] AB/C severe to critical cases (n= 6). Expression of mHLA-DR in healthy subjects (n = 15) was 43,161 [25,147-89,846] AB/C. Based on the Mann-Whitney U test, the mHLA-DR expression in COVID-19 patients significantly differed from the mHLA-DR expression in healthy subjects (p = 0.010). CONCLUSION: The level of mHLA-DR expression in COVID-19 patients was lower and significantly different from healthy subjects. Moreover, immunosuppression could be indicated by the decrease of mHLA-DR expression, which was below the reference range found in severe to critically ill COVID-19 patients.

Utility of Monocyte Expression of HLA-DR versus T Lymphocyte Frequency in the Assessment of COVID-19 Outcome.

Background: Dysregulated immunity is a hallmark of SARS-CoV-2 infection. Immune suppression is indicated by low monocyte expression of human leukocyte antigen D-related (mHLA-DR). T cells are important antiviral cells. We aimed to assess the role of mHLA-DR and T lymphocyte frequency in predicting COVID-19 severity. Patients and Methods: This cross-sectional study enrolled 97 SARS-CoV-2 positive patients, including mild to moderate (n = 49) and severe cases admitted to intensive care unit (ICU) (n = 48). These ICU cases were further subdivided into survivors (n = 35) and non-survivors (n = 13). Results: Severe cases had a significant decrease in the mHLA-DR mean fluorescence intensity (MFI) and T lymphocyte percentage compared to mild to moderate cases (P<0.001). Non-survivors had a lower T lymphocyte percentage (P=0.004) than survivors. The mHLA-DR MFI and T lymphocyte percentage correlated with oxygen saturation (r=0.632, P<0.001) and (r=0.669, P<0.001), respectively. According to the ROC curves, mHLA-DR MFI, at a cutoff of 143 and an AUC of 0.9, is a reliable biomarker for distinguishing severe COVID-19 cases, with 89.6% sensitivity and 81.6% specificity, while T lymphocyte frequency had 81.3% sensitivity and 81.6% specificity at a cutoff of 54.4% and an AUC of 0.9. The T lymphocyte percentage as a predictor of ICU survival at a cutoff of 38.995% exhibited 100% sensitivity and 57.1% specificity. According to multivariate regression analysis, reduced mHLA-DR MFI and T lymphocyte percentage are independent predictors of COVID-19 severity (OR = 0.976, 95% CI: 0.955-0.997, P = 0.025) and (OR = 0.849, 95% CI: 0.741-0.972, P = 0.018), respectively. Conclusion: Reduced mHLA-DR expression and T-lymphocyte percentage are independent predictors of COVID-19 severity. Oxygen saturation percentage is correlated with mHLA-DR MFI and T lymphocyte frequency. The T lymphocyte frequency is a proposed predictor of COVID-19 survival in ICU admitted patients.

Case Report: Interferon- γ Rescues Monocytic Human Leukocyte Antigen Receptor (mHLA-DR) Function in a COVID-19 Patient With ARDS and Superinfection With Multiple MDR 4MRGN Bacterial Strains.

Background: CD14+ monocytes present antigens to adaptive immune cells via monocytic human leukocyte antigen receptor (mHLA-DR), which is described as an immunological synapse. Reduced levels of mHLA-DR can display an acquired immune defect, which is often found in sepsis and predisposes for secondary infections and fatal outcomes. Monocytic HLA-DR expression is reliably induced by interferon- γ (IFNγ) therapy. Case Report: We report a case of multidrug-resistant superinfected COVID-19 acute respiratory distress syndrome (ARDS) on extracorporeal membrane oxygenation (ECMO) support. The resistance profiles of the detected Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Citrobacter freundii isolates were equipped with resistance to all four antibiotic classes including carbapenems (4MRGN) and Cefiderocol in the case of K. pneumoniae. A causal therapeutic antibiotic strategy was not available. Therefore, we measured the immune status of the patient aiming to identify a potential acquired immune deficiency. Monocyte HLA-DR expression identified by FACS analysis revealed an expression level of 34% positive monocytes and suggested severe immunosuppression. We indicated IFNγ therapy, which resulted in a rapid increase in mHLA-DR expression (96%), rapid resolution of invasive bloodstream infection, and discharge from the hospital on day 70. Discussion: Superinfection is a dangerous complication of COVID-19 pneumonia, and sepsis-induced immunosuppression is a risk factor for it. Immunosuppression is expressed by a disturbed antigen presentation of monocytes to cells of the adaptive immune system. The case presented here is remarkable as no validated antibiotic regimen existed against the detected bacterial pathogens causing bloodstream infection and severe pneumonia in a patient suffering from COVID-19 ARDS. Possible restoration of the patient's own immunity by IFNγ was a plausible option to boost the patient's immune system, eliminate the identified 4MRGNs, and allow for lung recovery. This led to the conclusion that immune status monitoring is useful in complicated COVID-19-ARDS and that concomitant IFNγ therapy may support antibiotic strategies. Conclusion: After a compromised immune system has been detected by suppressed mHLA-DR levels, the immune system can be safely reactivated by IFNγ.

Myeloid phenotypes in severe COVID-19 predict secondary infection and mortality: a pilot study.

BACKGROUND: De-regulated host response to severe coronavirus disease 2019 (COVID-19), directly referring to the concept of sepsis-associated immunological dysregulation, seems to be a strong signature of severe COVID-19. Myeloid cells phenotyping is well recognized to diagnose critical illness-induced immunodepression in sepsis and has not been well characterized in COVID-19. The aim of this study is to review phenotypic characteristics of myeloid cells and evaluate their relations with the occurrence of secondary infection and mortality in patients with COVID-19 admitted in an intensive care unit. METHODS: Retrospective analysis of the circulating myeloid cells phenotypes of adult COVID-19 critically ill patients. Phenotyping circulating immune cells was performed by flow cytometry daily for routine analysis and twice weekly for lymphocytes and monocytes subpopulations analysis, as well as monocyte human leukocyte antigen (mHLA)-DR expression. RESULTS: Out of the 29 critically ill adult patients with severe COVID-19 analyzed, 12 (41.4%) developed secondary infection and six patients died during their stay. Monocyte HLA-DR kinetics was significantly different between patients developing secondary infection and those without, respectively, at day 5-7 and 8-10 following admission. The monocytes myeloid-derived suppressor cells to total monocytes ratio was associated with 28- and 60-day mortality. Those myeloid characteristics suggest three phenotypes: hyperactivated monocyte/macrophage is significantly associated with mortality, whereas persistent immunodepression is associated with secondary infection occurrence compared to transient immunodepression. CONCLUSIONS: Myeloid phenotypes of critically ill COVID-19 patients may be associated with development of secondary infection, 28- and 60-day mortality.