Immunohistochemistry of ultrastructural changes in scarring lupus erythematosus.

P>Background. The various clinical types of lupus erythematosus (LE) show an essentially similar histological picture, and the subsets of LE cannot easily be distinguished by histology alone. However, there is an important clinical difference: lesions of discoid LE (DLE) cause scarring, particularly on the scalp, whereas lesions of subacute and acute LE heal without scarring. The focal thickening of the basement membrane zone (BMZ) in DLE lesions represents an important histopathological finding, and there is little known about the nature of these alterations at the BMZ level. Aim. To investigate BMZ alterations in the basement membrane zone (BMZ) in cutaneous LE (CLE) by immunohistochemistry. Methods. Skin biopsies from 30 patients with CLE [DLE and subacute CLE (SCLE)] and from 10 controls were studied using antibodies to cytokeratin 5, cytokeratin 14, bullous pemphigoid (BP)180, BP230, plectin, laminin 5, collagen IV and collagen VII. Results. There was increased expression of components of the lamina lucida, lamina densa and anchoring fibrils in active DLE, whereas expression was normal in SCLE and control tissues, and in areas of scarring in DLE. In addition, higher expression of the hemidesmosome-associated antigens (BP230 and plectin) was found in active DLE. The expression of other antigens was similar in all tissues examined. Conclusions. These alterations in the BMZ suggest that the BMZ may react in a different way in active DLE than in SCLE, and that the BMZ may remodel in different ways. These immunohistochemical differences may provide a new method of histological differentiation between the various LE subtypes.