New non-invasive method for evaluation of the stratum corneum structure in diseases with abnormal keratinization by immunofluorescence microscopy of desmoglein 1 distribution in tape-stripped samples.

The corneodesmosomes in the stratum corneum are critical for the maintenance of stratum corneum integrity. To evaluate the normal and diseased keratinization states in the epidermis, we studied the distribution of desmoglein 1 (DSG1), a major component of corneodesmosomes, in samples of the stratum corneum obtained by tape stripping, a non-invasive method. Samples were collected from lesional skin of four patients with psoriasis and three with lichen planus, and from non-lesional skin of three volunteers. Upper stratum corneum cells were obtained by tape stripping and skin biopsies were obtained from adjacent sites. Tape-stripped samples were examined by immunofluorescence microscopy using anti-DSG1 monoclonal antibody, in combination with histopathology of skin biopsies. In normal human stratum corneum, which shows basket-woven orthokeratosis, DSG1-containing fluorescent dots were distributed on the lateral cell-cell contact areas of plasma membrane, but not on the dorsal/ventral plasma membrane, and formed a well-ordered hexagonal network structure. In psoriatic stratum corneum, fluorescent dots were distributed throughout the cell membrane at ventral aspects of corneocytes as well as at the lateral cell-cell contacts. In lichen planus, fluorescent dots were distributed homogeneously and/or heterogeneously on the ventral surface in some cells. Adjacent cells lacked DSG1 at the lateral cell-cell contacts, but were instead separated by distinctive black-gap lines. These results suggest that the intercellular adhesion by DSG1 may depend on the lateral plasma membrane in normal human stratum corneum, on the dorsal/ventral plasma membrane in lichen planus, and on both lateral and dorsal/ventral plasma membranes in psoriatic stratum corneum. Tape stripping and DSG1 immunofluorescence visualizes adhesion features of corneocytes and has considerable potential for evaluation of abnormal keratinization and the process of healing in response to treatment.