Bone marrow transplantation in the rat. V. Lymphoid cell subclasses in the target organs during acute graft-versus-host disease.

The distribution of white cell subclasses in different lymphoid (bone marrow, spleen, and blood) and parenchymal (liver, skin, lungs, and gut) target organs was studied after bone marrow transplantation in the rat. BN rats were irradiated and transplanted with 60-80 X 10(6) Lew (allogeneic) or BN (syngeneic) bone marrow cells. The recovery of lymphocytes was somewhat elevated in the bone marrow and spleen, slightly decreased in the blood, and markedly higher in the liver and skin in the allograft compared with the syngeneic graft recipient. A mild lymphocytic bronchitis was present in the lungs of the allografted animal, and the gut was hypocellular throughout the observation period. The total recovery of different lymphocyte subclasses; pan T, T helper, T suppressor-killer, class-II-positive cells, and surface-Ig-positive B cells in the different lymphoid organs--i.e., bone marrow, spleen, and blood--was similar in allogeneic compared with syngeneic graft recipients. In the liver and skin, which are the major target organs of acute graft-versus-host disease (aGVHD) in the rat, there was a massive infiltration of different T cell subclasses; high numbers of B cells were also seen in the liver. There was no difference in the T helper/T suppressor-killer ratio in the lymphoid organs or the liver of allograft compared with syngeneic graft recipients; in the skin and lungs the ratio was reduced more in the allograft compared with syngeneic graft recipient, whereas in the gut the situation was the opposite. These observations emphasize regional differences in the structure of inflammation in the different parenchymal target organs of aGVHD in the rat.