Immunolocalization of FXIIIa+ dendritic cells in human burn wounds

Dermal dendrocytes constitute a population of indigenous antigen-presenting cells that have been implicated in dermal inflammation and may have a role in wound healing. They are identified by expression of the transglutaminase coagulation Factor XIIIa (FXIIIa) and a perivascular distribution in the papillary dermis. In this study, we used immunohistochemistry to localize and characterize FXIIIa+ cells in healing burn wounds. Wound specimens from Postburn Days 2, 3, 4, 5, 6, 8, 9, 10, 11, 15, 30, and 49 were collected from 18 patients at the time of excision and grafting, processed for immunolabeling, and labeled with an antibody to FXIIIa. Tissue sections were also double-labeled with the anti-FXIIIa and with antibodies to CD68, specific for macrophages, CD45, specific for bone marrow-derived cells, and proliferating cell nuclear antigen (PCNA) for proliferation. Antigen-presenting status was evaluated using an antibody to the major histocompatibility complex HLA-DR. The dermis subjacent to the tongue of proliferating epithelium at the wound edge had increased numbers of FXIIIa+ dendritic cells compared to the cellular distribution in uninjured skin. FXIIIa+ dendritic cells were absent from the burned dermis on all postburn days examined in this study. However, capillaries in the deep dermis had a FXIIIa+ granular staining pattern. CD68+ cells and CD45+ cells were present throughout the wound bed at all stages of healing, indicating an inflammatory cell response in the injured dermis. Antibodies to PCNA did not colocalize to FXIIIa+ cells, suggesting that the dermal dendrocytes were not proliferating. The antibody to HLA-DR localized to some, but not all of the FXIIIa+ dendritic cells.(ABSTRACT TRUNCATED AT 250 WORDS)