Novel class I-like molecule expressed on a murine leukemia virus-transformed cell line

A retrovirus-induced tumor cell line, which expresses no H-2K or H-2D class I molecules, appears to express a tumor-specific transplantation antigen which induces tumor rejection in vivo and cytotoxic T lymphocyte generation in vitro without prior immunization and thus resembles class I molecules. In addition, although these tumor cells express no detectable class I molecules, they do express beta 2 microglobulin and a 55- to 60-kDa beta 2 microglobulin-associated protein. Northern analysis demonstrated that these cells express no RNA hybridizing to class I probes, suggesting that neither the tumor-specific transplantation antigen nor the beta 2 microglobulin-associated protein, if these are different, are encoded by known class I genes.