Immunohistochemical study of graft-versus-host reaction (GVHR)-type drug eruptions

Skin biopsies of graft-versus-host reaction (GVHR)-type drug eruptions in the acute phase were compared immunohistochemically with those in the chronic phase and also with non-GVHR type drug eruptions in the acute phase. Predominance of CD8+ T cells in the epidermal infiltrates, reduction in the number of epidermal OKT6+ dendritic cells (Langerhans cells), and increased expression of HLA-DR and ICAM-1 on keratinocytes were observed in the acute phase of GVHR-type, but not in either the chronic phase of GVHR-type or the acute non-GVHR type. These findings were similar to those of previous reports on skin lesions of acute GVH disease (GVHD) seen after bone marrow transplantation. Therefore, immunohistochemistry is not useful for differential diagnosis between acute GVHR-type drug eruptions and acute cutaneous GVHD. These findings also indicate that similar immunomechanisms may be involved in the pathogenesis of both GVHR-type drug eruptions and cutaneous GVHD.