Study Reveals How COVID-19 Reprograms White Blood Cells to Suppress the Immune Response

Recent research from Johns Hopkins Medicine, the Johns Hopkins Bloomberg School of Public Health, and the Whiting School of Engineering has uncovered a novel mechanism by which SARS-CoV-2, the virus responsible for COVID-19, interferes with the immune system. The study shows that neutrophils, which are the most abundant white blood cells in humans and typically play a crucial role in fighting infections, can be manipulated by the virus to transform into cells that suppress immune responses instead.

This transformation involves neutrophils releasing their granular contents and differentiating into a cell type known as polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). These PMN-MDSCs are known for their ability to inhibit the activity of T lymphocytes, which are vital for clearing viral infections. The researchers found that in severe COVID-19 cases, neutrophils not only degranulate but also exhibit increased expression of markers like LOX-1 and PD-L1, which are associated with immune suppression.

Laboratory experiments demonstrated that exposure of neutrophils to SARS-CoV-2 prompts their differentiation into PMN-MDSCs, capable of limiting T-cell proliferation and cytokine release. Interestingly, this reprogramming appears specific to SARS-CoV-2, as similar effects were not observed with H1N1 influenza, indicating that not all viruses induce such changes.

Understanding this immune suppression mechanism could explain why severe COVID-19 cases involve a compromised immune response and exaggerated inflammation. The study also explores potential therapeutic strategies; for instance, blocking PD-L1 with antibodies could reduce T-cell suppression and enhance immune function, offering a promising approach for treating severe COVID-19.

Overall, these findings suggest that SARS-CoV-2 has the ability to directly impair immune defenses by converting neutrophils into immune suppressors, potentially contributing to disease severity. Further research into these processes may lead to new therapies aimed at preventing neutrophil reprogramming and bolstering immune responses against COVID-19.

Source: https://medicalxpress.com/news/2025-05-covid-virus-reprograms-infection-fighters.html