Origin and subset distribution of peripheral blood dendritic cells in patients with chronic graft-versus-host disease

Background. After allogeneic hematopoietic stem cell transplantation, donor T cells interact with an antigen-presenting cell environment that is distorted in number, level of activation, and origin. The role of antigen presentation in the development of chronic graft-versus host disease (cGVHD) is unknown. Methods. The numberand origin of peripheral blood immature myeloid (CD19(-) CD1c(+)) and plasmacytoid (BDCA-2(+)) dendritic cells (DCs) was determined in 30 patients at more than 100 days after allogeneic hematopoietic stem cell transplantation. Results. Patients with cGVHD had significantly higher plasmacytoid DC numbers than individuals without this complication (9.1+/-2.0 x 10(6)/L versus 3.8+/-0.6 x 10(6)/L, P=0.025). Chimerism studies demonstrated that DCs in patients with cGVHD were exclusively of donor origin, whereas persistence of host DCs was observed in some control patients. Conclusions. The antigen-presenting cell environment in patients with cGVHD, as represented by immature blood DCs, is of donor origin but distorted in terms of subset distribution.