Background Recent studies have suggested that dermal dendritic cells (DDCs) may play a part in maintaining the structure of the dermis and in dermal immune modulation. Alteration in the population of DDCs has been noted in localized and systemic scleroderma, particularly a decline in the number of CD34+ DDCs.
Objectives To define the alteration of the DDC populations with respect to the histological stage of morphoea.
Methods We examined 33 biopsies of morphoea, categorized into four histological stages, and examined the DDC population (CD34+ DDCs and factor XIIIa+ DDCs), the lymphocytic infiltrate, and tenascin (extracellular matrix glycoprotein) and transforming growth factor (TGF)-β1 expression in each biopsy.
Results As the dermis became less inflammatory and more sclerotic, there was a significant decline in the number of CD34+ DDCs and an increase in the number of factor XIIIa+ DDCs. The pan-T-cell infiltrate (UCHL-1/CD45RO) and tenascin deposition exhibited a similar pattern, with elevated expression in inflammatory stages and a decrease in expression as the dermis became sclerotic. TGF-β1 was significantly elevated in three of the four histological stages of morphoea, in both the inflammatory and sclerotic stages. The proposed four-stage histological analysis of morphoea biopsies was a useful basis for studying dendritic cells and mediators in cutaneous sclerosis.
Conclusions Our study indicates that there is a reciprocal relationship between CD34+ DDCs and factor XIIIa+ DDCs in morphoea that correlates with the relative degrees of inflammation and sclerosis.