What is the mechanism underlying eosinopenia in COVID-19 patients?
Eosinopenia is commonly reported in severe COVID-19.54,55 The underlying mechanisms are largely unknown and most likely multifactorial. A number of possible explanations have been proposed: decreased eosinophilopoiesis; defective eosinophil egression from the bone marrow; and eosinophil apoptosis induced by type 1 IFN released during the acute infection.50 Also, increased eosinophil migration and retention within inflamed tissues has been described,56 but disputed for the aforementioned reasons.51