The clinical and immunological characteristics in fatal severe fever with thrombocytopenia syndrome virus (SFTSV) infection.

OBJECTIVE: This study aimed to make a comprehensive evaluation of peripheral immune profiles for further understanding the immunopathogenesis of severe fever with thrombocytopenia syndrome (SFTS).

METHODS: Forty-seven patients with SFTS virus infection were included, of which 24 were deceased. The percentages, absolute numbers, phenotype of lymphocyte subsets were detected by flow cytometry.

RESULTS: In patients with SFTS, the numbers of CD3+ T, CD4+ T, CD8+ T and NKT cells were decreased compared with healthy controls (HCs), accompanied with highly active and exhausted phenotypes for T cells, and overproliferating plasmablasts. High inflammatory status, dysregulation of coagulation and host immune response were more obvious in deceased patients than that of survivors. Higher levels of PCT, IL-6, IL-10, TNF-α, APTT, TT and the occurrence of hemophagocytic lymphohistiocytosis were poor prognostic indicators of SFTS.

CONCLUSIONS: The evaluation of immunological markers in combination with laboratory tests has critical value for selecting prognostic markers and potential treatment target.