Expression of interferon-γ receptors on murine oligodendrocytes and its regulation by cytokines and mitogens

Abstract

Interferon-γ (IFN-γ) is a cytokine known to exert an important immunological role on astrocytes and oligodendrocytes. As a receptor for IFN-γ has been demonstrated on murine astrocytes, we have searched for a specific receptor on the cell surface of pure mouse oligodendrocytes maintained in tissue culture. Using recombinant murine IFN-γ labelled with 125I, we have established the basic physicochemical parameters of the binding. A single receptor was found with a K(d) of 1 x 10-9 M. The number of receptors per cell was 3000-4000 and its molecular weight, as determined by cross-linking experiments, is 87 000. The binding of IFN-γ to its oligodendrocyte receptor is saturable, specific and temperature-dependent. The receptor-IFN-γ complex is quickly endocytosed at 37° (the half-time of maximal internalization is around 1 min). Some cytokines, such as interleukin-1α and interleukin-6, up-regulated the expression of the oligodendrocyte receptor, but others, such as tumour necrosis factor-α, did not. A dramatic increase in receptor expression is induced by lipopolysaccharide but it is not detectable after treatment with concanavalin A.