Association between anticonvulsant hypersensitivity syndrome and human herpesvirus 6 reactivation and hypogammaglobulinemia.

BACKGROUND Anticonvulsant hypersensitivity syndrome (AHS) is a life-threatening, drug-induced, multiorgan system reaction. The identification of predisposing factors is clearly needed to predict the incidence and outcome of AHS; attention has recently been focused on reactivation of human herpesvirus 6 (HHV-6). OBJECTIVE To determine whether immunosuppressive conditions that can allow HHV-6 reactivation could be specifically detected in association with the onset of AHS. DESIGN We analyzed patients with AHS who were treated during 1997-2002. Two groups of patients receiving anticonvulsants served as controls. SETTING Department of Dermatology, Kyorin University School of Medicine, Tokyo, Japan. Patients Ten patients with AHS. MAIN OUTCOME MEASURES The results of serologic tests for antibody titers for various viruses, including HHV-6, HHV-6 DNA detection by real-time polymerase chain reaction, immunoglobulin levels by turbidimetric immunoassay, IgG subclass levels by nephelometry, and CD19(+) B-cell counts by flow cytometric analysis, were sequentially assessed. RESULTS Serum IgG levels (mean, 745 mg/dL) and circulating B-cell counts (mean, 88/ micro L) in patients with AHS were significantly decreased at onset compared with control groups (P<.001 and P =.007, respectively). These alterations returned to normal on full recovery. Reactivation of HHV-6 as judged by a greater than 4-fold increase in HHV-6 IgG titers was exclusively detected in most patients with AHS associated with decreased IgG levels and B-cell counts. CONCLUSIONS A decrease in immunoglobulin levels and B-cell counts can be associated with HHV-6 reactivation and the subsequent onset of AHS. These immunological alterations might be a useful predictor of the development of AHS.