IMMUNOHISTOCHEMICAL ANALYSIS OF T-CELL PHENOTYPES IN PATIENTS WITH GRAFT-VERSUS-HOST DISEASE FOLLOWING ALLOGENEIC BONE-MARROW TRANSPLANTATION

Allogeneic bone marrow transplantation has become the therapy of choic e in many cases of hematologic malignancy. In both matched related don or transplants-and, to a greater degree, in unrelated donor transplant situations-a major complication of the procedure is GVHD. This proble m is caused by mature T cells in the graft, which also facilitate engr aftment, and mediate an antitumor effect to reduce relapse. In order t o further characterize the T cells that are present at the GVHD site o f injury, we have studied 134 fresh tissue biopsies using immunohistoc hemical methods from 50 consecutive ABMT recipients clinically suspect ed of having acute GVHD. Antibodies specific for T cells, T cell recep tor subsets, B cells, and NK cells were used to characterize the lymph ocytic infiltrate in the biopsy tissue from GVHD patients. The data sh owed that the majority of lymphocytes that had infiltrated the epithel ium or epidermis were CD3+ T cells. Using antibodies that distinguishe d the alpha/beta (beta F1) from the gamma/delta TCR (TCR delta 1)-expr essing T cells, we observed that the lymphocytic infiltrates from invo lved tissues of the gastrointestinal tract, skin, and liver are almost exclusively derived from the alpha/beta expressing T cell subset, and are of the memory cell subset of T cells (CD45RO). This is in contras t to some examples from other disease states, in which a significant p roportion of the lymphocytes that infiltrate the epidermal layers are of the gamma/delta type.