Immunohistology of skin and rectum biopsies in bone marrow transplant recipients

We have studied histological and immunohistological specimens of 39 skin biopsies from 21, and 30 rectal biopsies from 17 bone marrow transplant recipients. The biopsies were taken before transplantation, during acute and chronic graft-versus-host disease (GVHD), and at times with no GVHD. In biopsies taken during cutaneous aGVHD grade I to III, epithelial changes were seen in 16/23 biopsies. The cutaneous infiltrates during aGVHD consisted of CD2-, CD4-, CD8- and FMC-33-positive cells both in the epithelium and in the dermis. CD57-positive NK cells were also detected in most biopsies. During chronic GVHD the cutaneous cellular infiltrates were similar to those seen in moderate aGVHD, i.e. both CD4- and CD8-positive lymphoid cells were present. When the biopsy was taken after the beginning of corticosteroid treatment for aGVHD, or at times when the patient did not have GVHD symptoms, the cellular infiltrates were considerably smaller in the dermis. During clinical intestinal aGVHD mucosal epithelial changes were relatively uncommon; instead, increased numbers of both CD4- and CD8-positive lymphocytes in the lamina propria (LP) were seen in 11/13 samples. During chronic GVHD the number of CD4-positive cells exceeded that of CD8-positive cells in the LP, and the large lymphoid infiltrates also reached the muscularis mucosae. In rectal biopsies the differences were not so prominent because most of the pretransplant biopsies showed CD2-, CD4-, CD8- and CD57-positive lymphocytes both in the lamina propria and epithelium.