Decreased monocyte subsets and TLR4-mediated functions in patients with acute severe fever with thrombocytopenia syndrome (SFTS)

•The roles of monocytes in the pathogenesis of acute severe fever with thrombocytopenia syndrome (SFTS) were studied.•Cell counts and percentages of monocytes in peripheral blood were significantly reduced in acute SFTS patients.•Despite their higher basal toll-like receptor 4 expression, monocytes from acute SFTS patients were found to be compromised regarding the production of tumor necrosis factor alpha upon lipopolysaccharide stimulation.