Bone marrow transplantation in the rat. B lymphocyte activation in acute graft-versus-host disease.

We have isolated the white cells from the bone marrow, spleen, and blood of a rat recipient of a bone marrow allograft and the inflammatory leukocytes from the recipient skin, lung, gut, and liver (the parenchymal target organs for acute graft-versus-host disease (aGVHD)) and compared the number of immunoglobulin-synthesizing and releasing cells in these cell populations to corresponding compartments of a syngeneic graft recipient. Bone marrow transplantation was associated in the early phase with marked immunoglobulin production in the cells of bone marrow, spleen, and blood of the allograft recipient; as, however, a similar response occurred in the syngeneic graft recipient we conclude that this is related to reconstitution rather than to aGVHD. Later, during aGVHD, the number of immunoglobulin releasing cells decreased significantly in the spleen and bone marrow of the allografted animal. In clear contrast, in the liver--but not in skin, lung, or gut--very few immunoglobulin-releasing cells were observed in the syngeneic graft recipient, whereas in the allograft recipient a very strong and significantly higher immunoglobulin synthesis and release was seen coinciding with the inflammatory episode of aGVHD in the liver.