Megakaryocytes and Platelets in Immune and Inflammatory Responses and in COVID-19

Platelets-small cells which circulate in abundance in the bloodstream-are traditionally known for their ability to form clots and stop bleeding. Recent studies, however, have shown that platelets and their parent cells, megakaryocytes, also play a role in inflammation and infection. University of Utah Health investigators Robert Campbell, PhD, and Matthew Rondina, MD, and colleagues discovered that platelets and megakaryocytes respond robustly to infection, including COVID-19. These infection-driven changes in platelets activate clotting mechanisms and thus may contribute to the blood clots that complicate COVID-19 infection. Interestingly, Campell and Rondina and their collaborators also found that platelets and megakaryocytes demonstrate robust anti-viral defense properties that inhibit the spread of infection. Therefore, megakaryocytes from patients with genetic mutations in these anti-viral defense proteins are more susceptible to infection. These findings helped identify new pathways that regulate host responses to viral infection, and platelets are now being targeted therapeutically in patients with COVID-19.