Different effects of pemphigus antibody and plasmin on the distribution of keratin intermediate filaments and desmoplakins between cultured oral and epidermal keratinocytes.

In order to clarify the molecular mechanism of blister formation in oral mucosa in pemphigus vulgaris (PV) comparing with that in epidermis, we analyzed the effects of PV serum on the distribution of keratin intermediate filaments (KIFs) and desmoplakins in oral as well as epidermal cultured keratinocytes by immunofluorescence microscopy using anti-keratin and anti-desmoplakin I/II monoclonal antibodies. After incubation with PV serum for 96 h at 37 degrees C, clusters of anti-keratin positive dots were formed around the nucleus in some of the keratinocytes from normal gingiva and soft palate but not in keratinocytes from tongue and skin, and desmoplakins also changed their distribution from linear arrangement at cell-cell contacts to clusters of dots around the nucleus in gingiva but not in epidermal keratinocytes. The dotted structures similar to those induced by pemphigus serum were formed also by incubation with human plasmin in gingival keratinocytes. However, no dot-formation of keratins was induced in these cells after incubation with trypsin. Furthermore, in epidermal keratinocytes, no keratin-dot formation was observed even after incubation with plasmin or trypsin. These results suggest that the dotted structures of KIFs caused by PV serum and plasmin might be a feature characteristic for the response of oral keratinocytes to PV serum and that there are some distinct differences in susceptibility to, and mode of, bulla formation between oral epithelium and epidermis.