LANGERHANS CELLS ARE DEPLETED IN CHRONIC GRAFT-VERSUS-HOST DISEASE

Aims-To measure Langerhans' cells in skin of patients treated by bone marrow transplantation who developed chronic graft versus host disease (GvHD); to determine whether the reduction in Langerhans' cells resul ted directly from the GvHD or from other factors, such as the immunosu ppressive regimens used in bone marrow transplant patients. Patients a nd methods-Lesional and non-lesional skin specimens from nine patients with lichen planus-like lesions and three patients with sclerodermoid lesions were studied. Control skin specimens were taken from three pa tients undergoing breast reduction surgery. The number of Langerhans' cells/mm(2) and the area of Langerhans' cells as a percentage of total epidermis were measured by counting cells labelled with antihuman CD1 a. Results-A significant reduction in Langerhans' cell area and number were found in specimens with lesions (area 3.5%; number 507/mm(2)) co mpared with specimens without lesions (8.42%; 2375/mm(2)). In contrast , Langerhans' cell area and number in skin without lesions were simila r to controls (10.26%; 2968/mm(2)).Conclusions-Langerhans' cells were significantly reduced in skin with lesions of chronic GvHD but not in skin without lesions from the same patient, suggesting that the reduct ion is a direct consequence of GvHD and not linked to immunosuppressiv e drugs or late effects of conditioning regimens. In long term bone ma rrow transplant recipients, Langerhans' cells are derived mainly from the donor cells; therefore, this result suggests the occurrence of aut oreactive phenomenon in chronic GvHD.