Myeloid-derived suppressor cells: drivers of severe COVID-19 disease?


Falck-Jones et al., 2021. Graphical Abstract

SARS-COV-2 causes mild disease in most people, but turns fatal for others. Infection and diseases occur over a wide spectrum ranging from asymptomatic infection to multi-organ failure and death. An improved knowledge of immune responses during COVID-19 is needed to fully understand its pathogenesis and to identify factors that dictate disease severity, as this is relevant for the development of treatment strategies that will prevent COVID-19 mortality.

Myeloid-derived suppressor cells (MDSCs) are myeloid immune cells with an immature phenotype and strong T cell suppressive capacity. Scientists from Karolinska University investigated Monocytic Myeloid-derived suppressor cells (M-MDSCs) in COVID-19 patients across the spectrum of COVID-19 disease and compared this to influenza patients and healthy controls. They used blood and airways of COVID-19 patients across disease severity at multiple time-points. They found a striking association between the frequency of blood M-MDSCs and COVID-19 disease severity. The researchers discovered that purified M-MDSCs isolated from COVID-19 patients were functional and suppressed T cell proliferation and IFNγ production, partly through an Arg-1 dependent mechanism. The plasma Arg-1 levels were elevated in COVID-19 patients in a disease severity-dependent manner. They also found that early frequency of blood M-MDSCs predicted subsequent disease severity, suggesting that M-MDSCs are involved in the dysregulation of the immune response in COVID-19.

They concluded that M-MDSCs may predict disease outcome and that they may be used as a potential prognostic marker in COVID-19 patients.

Journal article: Falck-Jones, S., et al. (2021) Functional monocytic myeloid derived suppressor cells increase in blood but not airways and predict COVID19 severity. Journal of Clinical Investigation.

Summary by Margaret Oluwatoyin Japhet

International Union of Immunological SocietiesUniversity of South AfricaInstitute of Infectious Disease and Molecular MedicineElizabeth Glazer Pediatric Aids Foundation