Plasmacytoid dendritic cells diminution in peripheral blood is prevalent in drug reaction with eosinophilia and systemic symptoms and may precede human herpesvirus 6 reactivation

Abstract

Background: Plasmacytoid dendritic cells (pDCs) are implicated in the reactivation of human herpesvirus 6 (HHV-6) in drug reaction with eosinophilia and systemic symptoms (DRESS). Objectives: We aimed at identifying the alterations of circulating pDCs, basophils, and myeloid dendritic cells (mDCs) during the active stage of drug eruptions and the relationship between pDC alteration and HHV-6 reactivation in DRESS patients. Methods: Nine DRESS patients and twelve patients of other drug eruptions (ODE, including five cases of maculopapular eruptions (MPEs), five cases of Stevens-Johnson syndrome, and two cases of fixed drug eruption) were prospectively recruited. Blood samples were collected weekly for 2 consecutive weeks for flow cytometry of pDC, basophil, mDC, and detection of HHV-6 reactivation by serum anti-HHV-6 immunoglobulin G, or whole blood HHV-6 viral DNA by quantitative polymerase chain reaction. Results: The HHV-6 reactivation was exclusively seen in DRESS, and the pDC levels decreased in DRESS compared with ODE (P = 0.002) and (MPE, P = 0.021), with the timing of such decrease preceding HHV-6 reactivation. Conclusion: The decrease of pDC levels is significantly more common in DRESS patients and occurs before HHV-6 reactivation. The chronological sequence implies that the decrease of pDC may be crucial in the pathogenesis of viral reactivation.