Expression of Ia antigens in a murine T-lymphoma variant.

ESb, a cellular high metastatic variant derived from the murine T-cell lymphoma L5178Y (Eb), was found to synthesize Ia antigens. Ia-specific antibodies reacted with the ESb cells and precipitated Ia-like molecules from them. Two-dimensional gel electrophoretic analysis of immunoprecipitates of metabolically labeled ESb cells indicated that the Ia molecules on ESb were indistinguishable from those on murine B-cells. No Ia antigens were detectable on the parental tumor line Eb. Treatment with recombinant interferon-gamma (IFN-gamma) caused enhancement of class I histocompatibility antigen expression on Eb and ESb tumor lines. In ESb cells the expression of Ia and of Ia-associated invariant chain (Ii) was also increased upon IFN-gamma treatment. No induction of either Ia and Ii antigens was observed upon IFN-gamma treatment of the Eb line. These studies demonstrate a substantial difference between the Eb and ESb tumor lines with respect to: (i) constitutive expression of class II major histocompatibility antigens, and (ii) response to IFN-gamma treatment.