Assembly of epithelial cell fibrillins.

Fibrillins are large structural macromolecules that are components of connective tissue microfibrils. Fibrillin microfibrils have been found in association with basement membranes, where microfibrils appear to insert directly into the lamina densa. It is unknown whether fibrillins are limited to these sites of microfibril insertion or are present throughout the lamina densa. In this study, electron microscopic immunolocalization demonstrated the presence of fibrillin-1 throughout the lamina densa in the dermal-- epidermal junction. In order to investigate whether fibrillin microfibrils might be present in the lamina densa, epithelial cell cultures (WISH, HaCaT, and primary keratinocytes) were analyzed by immunofluorescence, immunoblotting, and extraction of microfibrils followed by rotary shadowing electron microscopy and compared to mesenchymal cell cultures (dermal fibroblasts and MG63 osteosarcoma). In contrast to mesenchymal cells, which elaborate a fibrillin fibril network, epithelial cells primarily deposit fibrillin into the extracellular matrix in a nonfibrillar form. Coculture experiments using human epithelial cells and mouse fibroblasts implicated the cells themselves in the assembly of fibrillin. The importance of the cell in this process was further underscored by novel data demonstrating that keratinocytes selectively secrete fibrillin-1 into the matrix and not into the medium and can differentiate between fibrillin-1 and fibrillin-2.

Pustular drug eruption due to bacampicilin hydrochloride in a patient with psoriasis.

We report a case of pustular drug eruption due to bacampicilin hydrochloride which developed in a patient with pustular psoriasis. The patient was a 45-year-old Japanese woman with psoriasis which started as pustular psoriasis twenty years previously. In 1994, she developed generalized erythema with pustules accompanied by high fever and liver injury. Clinical and histological findings of this pustular eruption were different from her previous episodes of pustular psoriasis. Erythemas and pustules disappeared and her abnormal transaminase returned to normal rapidly when she discontinued bacampicilin hydrochloride. Her positive reaction to a patch test and a lymphocyte stimulation test also suggested that our case had a pustular drug eruption rather than pustular psoriasis induced by a drug.

Ulcerative lichen planus: a rare variant of lichen planus.

A 54-year-old Japanese man with ulcerative lichen planus is reported. He had a painful erythema with ulcers on his soles and nail dystrophy. Mucous involvement was present on his lip. His hairs were intact. Histopathological findings confirmed the diagnosis of lichen planus.

2B1 antigen characteristically expressed on extracellular matrices of human malignant tumors is a large chondroitin sulfate proteoglycan, PG-M/versican.

2B1 is a monoclonal antibody against a large proteoglycan isolated from human yolk sac tumor (M. Sobue et al., Histochem. J., 21: 455-460, 1989). The antigen is expressed in a variety of embryonal tissues as well as most if not all malignant tumor tissues. However, the expression in normal adult tissues is limited to some tissues, such as the smooth muscle layers of the aorta. We characterized the 2B1 antigen isolated from the conditioned medium of human malignant fibrous histiocytoma and found that immunological and biochemical properties are identical to those of a large chondroitin sulfate proteoglycan, PG-M/versican. Partial amino acid sequences of peptides obtained from the core protein by V8 protease digestion and subsequent SDS-PAGE were detected in the reported amino acid sequence of human PG-M/versican with a complete identity. Furthermore, 2B1 was distinctly reactive to the expressed protein by transfection of the cDNA for the shortest form into mouse cells. The results indicate that the antigen is the PG-M core protein, and the epitope may be in one of the globular domains. It is thus likely that PG-M/versican is one of the extracellular matrix components characteristic of human malignant tumors.