Transplantation resistance to a murine plasmacytoma lacking MHC determinants.

A spontaneously arising murine plasmacytoma, HPC-202, derived from a BALB/c.H-2b congenic mouse that lacks any detectable H-2 determinants on its cell surface is described. However, the expression of H-2 determinants is inducible by interferon-gamma. The H-2 negative cell surface phenotype permits the HPC-202 tumor to escape H-2 allospecific cytotoxic cell lysis but not NK cell lysis, as well as to grow, to varying degrees, in some H-2 incompatible hosts. In those strains which exhibit a resistance to HPC-202 growth, resistance does not map to a single gene within the major histocompatibility complex of the mouse. Resistance is also radiosensitive and is therefore presumably due to a rapidly dividing cell population. The utility of this tumor as a model system to study both the non-H-2-restricted natural resistance to tumor growth, and the mechanism by which H-2 genes are regulated by cells is discussed.