Human herpesvirus 6 reactivation and inflammatory cytokine production in patients with drug-induced hypersensitivity syndrome.

BACKGROUND: Human herpesvirus 6 (HHV-6) reactivation has been suggested to modify the clinical features of drug induced hypersensitivity syndrome (DIHS). However, mechanisms for viral reactivation and modification of the clinical features remain unclear. OBJECTIVE: To determine whether cytokines play an important role in viral reactivation and modification of the clinical features. STUDY DESIGN: We examined the kinetics of serum cytokines and viral load in HHV-6 infections of six patients with DIHS. RESULTS: HHV-6 infection occurred three to four weeks after the onset of disease. Elevated TNF-alpha and IL-6 levels were observed to precede HHV-6 infection in four of the six patients. Although high levels of IL-6 were observed in samples collected prior to HHV-6 infection, the amounts of this cytokine significantly decreased to undetectable levels during viral infection in five of the six patients. Subsequently, serum IL-6 levels were increased after viral infection in five patients. IL-1beta levels were also increased at the time of viral infection in three of the six patients. Neither IL-4 nor IFN-gamma could be detected in any of the samples. CONCLUSION: These results demonstrate that cytokines play an important role in HHV-6 reactivation in patients with DIHS.