Emergence of foreign H-2-like cytotoxicity and transplantation targets on vaccinia and Moloney virus-infected Meth. A tumour cells.

Using cytotoxic effector cells of different anti-H-2 specificities, new cell-mediated lympholysis targets, normally undetected on Meth. A tumour cells, were shown after passage with vaccinia or Moloney virus. The H-2d CML targets on Meth. A cells recognized by B10.BR anti-B10.D2 effector cells were presented only after simultaneous vaccinia virus passage, while passage with Moloney virus caused the emergence of H-2b targets. Small but significant killing of vaccinia virus-passaged Meth.A was also obtained by anti-H-2k effector cells. These results are discussed in relation to in vivo experiments: retardation of tumour growth was noted in mice which had received several injections of vaccinia or Moloney virus, showing that the new CML targets were probably acting as transplantation targets.