Recombinant Human Interferon-αA/D Enhances the Expression of Ly-6A/E, Ly-6C, and TAP Antigens on Murine T Lymphocytes

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Abstract
The murine T-cell-associated antigens encoded by the Ly-6 locus transduce activation signals upon cross-linking on the cell surface and, thus, may be important for T-cell stimulation. Recently, we reported that the expression of Ly-6A/E and Ly-6C molecules is augmented in resting T cells after exposure to natural murine interferon (MuIFN)-α/β. Here, we examined further the specificity of this IFN effect on Ly-6 antigens. We used purified hybrid recombinant human (rHu) IFN-αA/D, which is known to be active on mouse cells. T cells from C57B1/6 and BALB/c mice were incubated for 2 days with various concentrations of rHuIFN-αA/D or of MuIFN-α/β. The levels of surface Ly-6A/E and Ly-6C antigens were quantified by flow cytofluorometry. The expression of the TAP (T-cell activating protein) molecule, another member of the Ly-6 antigen family, was also measured. All three types of antigens were enhanced by rHuIFN-αA/D in a dose-dependent fashion. The augmentation of the percentage of Ly-6-bearing cells induced by rHuIFN-αA/D was comparable to that induced by MuIFN-α/β. Although rHuIFN-αA/D was less active than MuIFN-α/β in increasing Ly-6A/E and TAP staining intensity, both IFNs were equally effective in increasing Ly-6C staining. Moreover, the induction of Ly-6 antigens by MuIFN-α/β, but not by rHuIFN-αA/D, was abrogated by an anti-IFN-α/β antiserum. Thus, although rHuIFN-αA/D and MuIFN-α/β are antigenically distinct, they share homology in their receptor binding domains such that both can trigger specific events leading to enhanced Ly-6 expression in murine T cells.