Dendritic cell chimerism in oral mucosa of transplanted patients affected by graft‐versus‐host disease

Objective Graft‐versus‐host disease ( GVHD ) is one of the main complications after haematopoietic stem cell transplantation. Clinical features of GVHD include either an acute ( aGVHD ) or a chronic ( cGVHD ) condition that affects locations such as the oral mucosa. While the involvement of the host's dendritic cells ( DC s) has been demonstrated in aGVHD , the origin (donor/host) and mechanisms underlying oral cGVHD have not been completely elucidated. In this study, we intend to determine the origin of DC s present in mucosal tissue biopsies from the oral cavity of transplanted patients affected by cGVHD . Methods We purified DC s, from oral biopsies of three patients with cGVHD , through immunobeads and subsequently performed DNA extraction. The origin of the obtained DC s was determined by PCR amplification of 13 informative short tandem repeat ( STR ) alleles. We also characterised the DC s phenotype and the inflammatory infiltrate from biopsies of two patients by immunohistochemistry. Results Clinical and histological features of the biopsies were concordant with oral cGVHD . We identified CD 11c‐, CD 207‐ and CD 1a‐positive cells in the epithelium and beneath the basal layer. Purification of DC s from the mucosa of patients affected by post‐transplantation cGVHD was >95%. PCR ‐ STR data analysis of DC s DNA showed that 100% of analysed cells were of donor origin in all of the evaluated patients. Conclusion Our results demonstrate that resident DC s isolated from the oral tissue of allotransplanted patients affected by cGVHD are originated from the donor. Further research will clarify the role of DC s in the development and/or severity of oral cGVHD .