Activation of Leukemia Viruses by Graft-Versus-Host and Mixed-Lymphocyte-Culture Reactions: Electron Microscopic Evidence of C-Type Particles

Summary A combined electron microscopic and virologic analysis showed murine leukemia viruses during graft-versus-host (GVH) and mixed-lymphocyte-culture (MLC) reactions. The viruses were detected by the XC cytopathogenicity test. C-type particles were seen in positive XC test plates, in the spleens of mice undergoing the GVH reaction, and in the MLC. Viruses were not found in any control group, including mice undergoing immune responses other than the GVH reaction. The specific association of the viruses with transformed lymphocytes suggests that the type of response represented by GVH and MLC reactions can activate leukemia viruses by a specific immunologic mechanism.