Immunovirological studies of fatal infectious mononucleosis in a patient with X-linked lymphoproliferative syndrome treated with intravenous immunoglobulin and interferon-α

We have studied a 19-year-old male with X-linked lymphoproliferative syndrome (XLP) and infectious mononucleosis (IM) who was treated with high-dose immunoglobulin (500 mg/kg/day) and recombinant interferon (IFN)-α (2 × 10⁶ IU/m²/day). Fulminant hepatitis was delayed; however, virus-associated hemophagocytic syndrome, cholestatic jaundice, and renal failure occurred terminally. Initially, nonspecific natural killer (NK) cell activity against K562 cells was normal but it gradually decreased. Although reactive T cells were markedly increased in his blood during the acute phase, spontaneous EBV-positive cell lines were easily established. Additionally, his mononuclear cells produced IFN-γ but not IFN-α prior to treatment. Based on results of in vitro studies, we conclude that both IFN-α and IFN-γ production are likely necessary for inhibiting EBV immortalization in vitro. Both IFN-α and -γ were produced in cultures of B95-8 EBV-infected mononuclear cells from EBV-seropositive healthy individuals. These results suggest that defective EBV-specific cytotoxic T cell activity accompanied with defective or discordant IFN-α and -γ production permitted the development of fatal IM in this patient. Combined treatment with immunoglobulin and IFN-α appeared to be partially effective during the early stage of this disease.