Differential up-regulation of HLA class I molecules on neuronal and glial cell lines by virus infection correlates with differential induction of IFN- β

Adult neurons normally lack the expression of MHC class I molecules, which has implications on virus clearance from the central nervous system. The author previously demonstrated that HLA class I up-regulation in measles virus (MV)-infected glial cells is primarily mediated by IFN-β. In contrast, this study demonstrates that MV-infection of the neuronal cell lines IMR-32 and CHP-126 fails to up-regulate HLA class I expression, which was associated with an inability of MV to induce IFN-β in the neuronal cell lines. However, treatment with IFN-β or coculture of the IMR-32 neuronal cell line with MV- infected glioma cells resulted in the up-regulation of HLA class I on the former, which could be neutralized by anti-IFN-β Ab. The inability of MV to up-regulate HLA class I expression on the neuronal cell line IMR-32 was not virus specific because similar findings were observed with mumps virus or stimulation with the synthetic dsRNA polyinosinic polycytidylic acid (PIPC). Induction of IFN-β gene expression by virus requires binding of NF-κB to the positive regulatory domain II element of the IFN-β promoter. Our studies indicate that MV, TNF-α, or PIPC induces NF-κB (p50 and p65 subunits) binding to positive regulatory domain II in the glioma cell line. In contrast, such activity was induced by TNF-α but not MV or PIPC in the neuronal cell line IMR-32. This indicated that HLA class I expression is differentially regulated in glial and neuronal cell lines in response to MV, which correlates with differential binding of NF-κB to the IFN-β promoter and induction of IFN-β gene expression.