Bone marrow transplantation in the rat. III. Structure of the liver inflammatory lesion in acute graft-versus-host disease.

The liver is a major parenchymal target organ of acute graft-versus-host disease (aGVHD) after bone marrow transplantation in the rat. The authors have analyzed the nature of cellular infiltrates in the liver using monoclonal antibodies against white cell subsets and investigated the anatomic distribution of the inflammatory cell subsets inside the liver parenchyma. Several types of white cells are present in a normal control liver: In the portal area the T-helper (Th) cells predominate, (surface) immunoglobulin-expressing B cells are present in ample numbers, and most of the phagocytes are Ia-positive. In the central vein area the T-suppressor/killer cells (Tsk) dominate, no B cells are present, and most of the phagocytes are Ia-negative. During aGVHD the number of T cells increases rapidly in the portal area; and after an initial strong increase, the Th/Tsk ratio decreases but remains still above 1. In the central vein area there is also an increase in the number of T cells, compared with that in the syngeneic recipient, but the Th/Tsk ratio rapidly decreases and remains uniformly below 1. During aGVHD the B cells entirely disappear from the portal area, whereas a small but distinct number of mature plasma cells with intracellular immunoglobulin appear in the central vein area. Following irradiation the Ia-positive phagocytic cells entirely disappear from the portal area and decrease distinctly in number in the central vein area. During aGVHD the number of Ia-positive phagocytes increases again in both locations. In the central vein area the positive phagocytes are seen over the background level, and, concomitantly, the Ia-negative phagocytes disappear.