Immunohistochemistry of cutaneous graft-versus-host disease after allogeneic bone marrow transplantation.

Graft-versus-host disease (GVHD) is an immunologically mediated disease occurring most frequently after allogeneic bone marrow transplantation. The aim of this study was to evaluate the contribution of immunohistochemistry in the diagnosis of cutaneous GVHD. Patients transplanted for either leukemia or beta-thalassemia were included in the study. Skin lesions of acute and chronic GVHD were examined both by direct immunofluorescence to detect immunoglobulin deposits and by an avidin-biotin-peroxidase complex technique to evaluate the inflammatory cell infiltrate. Epidermal and dermal fluorescent bodies (IgG and IgM) were frequently found in both acute and chronic GVHD. Most of the infiltrating cells were CD3+ T lymphocytes, with CD8+ cells representing the major cell population invading the epidermis both in acute GVHD and in chronic lichenoid GVHD. A small proportion of the dermal cells were CD14+ macrophages; no B cells were detected. HLA-DR, but not HLA-DQ antigens, were variably expressed by keratinocytes in all cases of acute GVHD and in chronic lichenoid GVHD. KL-1, a monoclonal antikeratin antibody specific for the 56.5 KD acidic polypeptide usually present in suprabasal keratinocytes, stained all epidermal layers, including the basal layer. Langerhans cells were dramatically reduced in number in the epidermis of both acute and chronic lichenoid GVHD. It is concluded that immunohistologic analysis may be supportive in the diagnosis of acute and early chronic lichenoid cutaneous GVHD.