Induction of HLA class II in HTLV-I infected neuronal cell lines

Human T-lymphotropic virus-I (HTLV-I) has been etiologically linked with HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP), a neurologic disease. The characteristic pathological finding in HAM/TSP is marked mononuclear infiltration of the CNS with destruction of the long tracts of the spinal cord. An increased expression of HLA surface antigens and cytokines in the CNS is associated with this inflammatory response. Furthermore, there is evidence for the presence of HTLV-I in HAM/TSP CNS specimens using in situ hybridization and polymerase chain reaction techniques. The relationship between HTLV-I infection of CNS cells and the observed upregulation of surface antigens in the CNS is not well understood. It has been previously demonstrated that HTLV-I infection of neuroblastoma cells leads to induction of HLA surface antigens. As an extension of these studies, HFGC and HCN-1a, neuronal cell lines of nontumorigenic origin, were infected with HTLV-I and the effect on HLA upregulation was studied. Infection of the neuronal cells was demonstrated by the presence of HTLV-I gp46 surface antigen on CD4 negative cells and by the in situ presence of HTLV-I RNA in neurofilament positive cells. Concurrent to HTLV-I infection, HLA class II surface antigen was observed on neurofilament positive cells. Upregulation of HLA class II was not observed in neuronal cells grown in the presence of interferon-gamma or tissue necrosis factor-alpha.