“In Situ” Visualization of a Graft-vs-Host Reaction

Abstract

Abstract Mice were lethally irradiated (950 R) and injected with xenogeneic (rat) or allogeneic spleen or bone marrow cells. Spleens were removed daily during the 1st week after treatment and tested for the presence of a graft-vs-host (GvH) or host-vs-graft (HvG) reaction using a modification of the Jerne hemolysis-in-agar technique. With either red blood cells or thymocytes as target cells, hemolytic and cytolytic foci indicative of a GvH reaction were detected within the first few days after treatment; peak activity was reached on day 6 in animals given xenogeneic spleen cells and on day 5 in those given allogeneic spleen cells. Injection of xenogeneic bone-marrow cells also yielded GvH foci, although the peak activity was delayed 1 day and was quantitatively less than with spleen cells. In the allogeneic model, bone marrow injection did not yield hemolytic or cytolytic foci. Control studies indicated that the foci obtained were mediated by a humoral factor, presumably an antibody, and were a result of complement-dependent specific antigen-antibody reactions. Although a pathogenic role of the humoral factor in GvH reactions is still to be defined, the ability to detect directly the presence of a GvH reaction represents a potentially important adjunct to further understanding of this disease process in man and animals.