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Tumor necrosis factor amplifies measles virus-mediated Ia induction on astrocytes
Abstract:
We describe the induction of Ia on cultured astrocytes by measles virus and the amplification of this induction by tumor necrosis factor (TNF). Measles virus induces Ia on rat astrocytes by direct interaction with these cells. TNF does not induce significant levels of Ia at any dose from 1 to 10,000 units/ml. As little as 10 units of TNF per ml, however, amplifies Ia-inducing signals generated by measles virus in astrocytes. In contrast, TNF and measles virus induce class I major histocompatibility complex (MHC) antigens, when applied individually, and TNF amplification of measles virus class I MHC induction is not apparent. The induction of either Ia or class I MHC antigens on rat astrocytes by measles virus does not depend on glial-derived soluble factors generated during infection. Since brain cells are normally lacking MHC antigens upon which T cells depend for interaction with antigen presenting cells, these data indicate that the ability of measles virus to directly stimulate MHC antigen expression and the ability of TNF to amplify Ia expression locally in the brain may be important in initiating cell-mediated immune response to viral infection.
Insights
Measles virus directly induces Ia antigens on astrocytes, and tumor necrosis factor (TNF) amplifies this response. This interaction is crucial for initiating cell-mediated immune responses to viral infections in the brain.
Area of Science:
- Neuroimmunology
- Virology
- Immunology
Background:
- Astrocytes play a crucial role in brain immunity.
- Major histocompatibility complex (MHC) antigens are vital for T cell interactions.
- Viral infections can trigger immune responses within the central nervous system.
Purpose of the Study:
- To investigate the effect of measles virus and tumor necrosis factor (TNF) on Ia antigen expression in cultured rat astrocytes.
- To determine the role of TNF in amplifying measles virus-induced Ia expression.
- To understand the implications for cell-mediated immunity in viral brain infections.
Main Methods:
- Cultured rat astrocytes were treated with measles virus and/or varying doses of TNF.
- Expression levels of Ia and class I MHC antigens were analyzed.
- The role of glial-derived soluble factors was assessed.
Main Results:
- Measles virus directly induced Ia antigen expression on astrocytes.
- TNF significantly amplified measles virus-induced Ia expression, even at low concentrations.
- Both measles virus and TNF induced class I MHC antigens individually, but TNF did not amplify this induction.
- Ia and class I MHC induction by measles virus did not rely on glial-derived factors.
Conclusions:
- Measles virus directly stimulates MHC antigen expression on astrocytes.
- TNF amplifies Ia expression induced by measles virus in astrocytes.
- These findings highlight a potential mechanism for initiating cell-mediated immune responses to viral infections in the brain.