Monocyte CD169 expression in COVID‐19 patients upon intensive care unit admission

Abstract

During the second surge of COVID‐19 in France (fall 2020), we assessed the expression of monocyte CD169 (i.e., Siglec‐1, one of the numerous IFN‐stimulated genes) upon admission to intensive care units of 45 patients with RT‐PCR‐confirmed SARS‐CoV2 pulmonary infection. Overall, CD169 expression was strongly induced on circulating monocytes of COVID‐19 patients compared with healthy donors and patients with bacterial sepsis. Beyond its contribution at the emergency department, CD169 testing may be also helpful for patients' triage at the ICU to rapidly reinforce suspicion of COVID‐19 etiology in patients with acute respiratory failure awaiting for PCR results for definitive diagnosis.

High CD169 Monocyte/Lymphocyte Ratio Reflects the Immunophenotyping Disruption and Predicts Oxygen Need in COVID-19 Patients

“…We also found an association of CD169 RMFI with PD1 expression, a crucial molecule for the induction and maintenance of peripheral tolerance, and of T cells stability and integrity. Indeed, the PD1/PD-L1 axis mediates potent inhibitory signals to block proliferation and function of T effector cells, inhibiting antiviral immunity[33].CD169 RMFI value was inversely correlated with the presence of specific SARS CoV-2 IgG in serum, confirming the data of previous studies[9,10]. Novelty, by the characterization of B cell compartment, we demonstrated the CD169 RMFI in untreated patients correlated directly with the percentage of naive and marginal B cells, while inversely with plasmablasts and switched B cells in all patients.…”

“…Accordingly, with recent works [9][10][11], the analysis we carried out on whole blood taken from COVID-19 patients at the time on admission, diagnosed by detection of SARS-CoV-2 RNA in nasopharyngeal swabs via Real Time PCR, showed higher levels of CD169 RMFI compared to healthy donors, which correlated with SARS-CoV-2 RNA expression detected in swabs. Interestingly, the increased CD169 RMFI values strongly associated with various clinical and biological parameters, were related not only with the patient's status at admission but also with the progression of the disease.…”

“…Indeed, it was shown that CD169 expression was strongly increased on circulating monocytes from COVID-19 patients compared to those from healthy donors or patients with bacterial sepsis. Increased CD169 expression was also associated with an increase of other activation markers including CD64, CD68, and CD38 [9]. Moreover, CD169+ monocytes were present in high numbers in the early stages of the disease and in the group including milder cases, where the monocyte compartment consisted almost exclusively of CD169 clusters [17,18].…”

“…Sixty-eight patients hospitalized, tested positive for SARS-CoV-2 RNA (COV), were screened for CD169 expression, using flow cytometry and compared to 57 healthy donors (HD). The ratio of the MFI of CD169 between monocytes and lymphocytes (CD169 RMFI) was calculated as previously described [9][10][11]. Figure 1A compares the CD169 RMFI in the HD and COV groups, showing that the CD169 RMFI was higher in patients with COV compared to HDs (median 16.17 ± 30.23 and 2.01±0.70 respectively, p<0.001).…”

“…Moreover, an increased expression of CD169 has been observed in monocytes from COVID-19 patients. In observational studies conducted during the COVID-19 outbreak in France, mCD169 expression was also associated with the SARS-CoV-2 infection in patients at hospital admission underlining the importance as early infection biomarker [9][10].…”