ULTRASTRUCTURAL ABNORMALITIES IN THE DERMAL PAPILLAE OF BOTH LESIONALAND CLINICALLY NORMAL FOLLICLES FROM ALOPECIA-AREATA SCALPS

Alopecia areata is a form of balding whose aetiology is uncertain. Alt hough the dermal papilla in the hair bulb regulates the follicle and m ay play a part in the pathogenesis of alopecia areata, its ultrastruct ure has not been well described. As clinically normal, i.e, non-baldin g, follicles from alopecia areata scalps show abnormalities at the lig ht microscope level, it would be expected that they should exhibit the earliest pathological changes involved in the dysfunction of the foll icle. This study was designed to investigate the ultrastructure of nor mal human scalp follicular dermal papillae and to see if changes occur red in the ultrastructure of dermal papillae from either lesional or n on-balding regions of alopecia areata. Normal dermal papillae containe d well formed fibroblast-like cells with large, oval nuclei and well-d eveloped endoplasmic reticulum; the cells were separated from each oth er by extracellular matrix containing small pieces of collagen and bas al lamina-like material. Dermal papillae from both clinically normal a nd lesional alopecia areata follicles were less well organized and the dermal papilla cells exhibited signs of cell injury and contained abn ormal amounts of pigment; an increased concentration of fibrous materi al in the extracellular matrix and thickening of the dermal papilla-ep ithelial junction were also seen. Follicles from lesional areas showed more pronounced changes than clinically normal ones. Ultrastructural abnormalities in the dermal papillae of clinically normal scalp follic les support the study of these follicles as a prime research target, T he changes detected suggest that dermal papilla cells in alopecia area ta would be less able to synthesize regulatory factors and that these may have more difficulty crossing into the epithelial compartment, The y are consistent with an early pathological role for the dermal papill a in alopecia areata, but do not distinguish whether this is a primary aetiological role or a secondary response to an insult elsewhere in t he follicle.