Recombinant human interferon-alpha A/D enhances the expression of Ly-6A/E, Ly-6C, and TAP antigens on murine T lymphocytes

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)-alpha/beta. Here, we examined further the specificity of this IFN effect on Ly-6 antigens. We used purified hybrid recombinant human (rHu) IFN-alpha A/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-alpha A/D or of MuIFN-alpha/beta. 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-alpha A/D in a dose-dependent fashion. The augmentation of the percentage of Ly-6-bearing cells induced by rHuIFN-alpha A/D was comparable to that induced by MuIFN-alpha/beta. Although rHuIFN-alpha A/D was less active than MuIFN-alpha/beta 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-alpha/beta, but not by rHuIFN-alpha A/D, was abrogated by an anti-IFN-alpha/beta antiserum. Thus, although rHuIFN-alpha A/D and MuIFN-alpha/beta 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.