Catherine Prost

Binding of autoantibodies is not restricted to desmosomes in pemphigus vulgaris

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune blistering diseases characterized by a loss of cell-cell adhesion and by autoantibodies directed against epidermal cadherins. PF antigen has been established as desmoglein I which is located strictly on the desmosome, whereas the precise ultrastructural localization of PV antigen remains unclear and controversial to date. To further investigate this question, we compared the location of immune deposits in 14 patients with PV and 10 patients with PF by both direct and indirect immunoelectron microscopy (IEM). Inclusion criteria were based upon clinical features, histological level of cleavage and characterization of circulating antibodies by Western blot on epithelial bovine tongue extracts. IEM was performed on unfixed 0.7-mm slices of skin for the direct technique or on normal skin for the indirect technique using peroxidase labelling. In PF, by both direct and indirect IEM, immune deposits were located on the extracellular part of desmosomes (desmoglea) in all the samples studied. In PV, by both direct and indirect IEM, deposits were situated on the desmoglea and along large portions of the keratinocyte membrane without desmosomal structures in 15 of the 18 samples studied and only on the desmoglea in 3 samples. These results suggest that, in contrast to PF, the target antigen in PV is not always restricted to desmosomes. As various types of adherens junctions have been reported to mediate cell adhesion in the epidermis, the PV antigen could be a component of desmosomes and of other focal adhesions.

Secondary Ion Emission Microanalysis: Applications to the Study of Human Skin*

SummarySecondary ion emission microanalysis is a new method of physical analysis recently applied in biology. The apparatus required (CAMECA SMI 300) enables pictures to be taken of the distribution of certain elements, with a space resolution of the order of 1 μm. Concentrations below 1 p.p.m. are perceptible for most elements.The present results are the first obtained for human skin sections. Investigation of the natural elements of normal skin reveals no particular accumulation. Elements foreign to the skin are easy to detect. We show here the distribution in the epidermis of clinical antiseptics applied locally.This method has two advantages compared to X-ray microanalysis. It is more sensitive and allows analysis of even the lightes elements. However, its use in skin penetration studies is limited because it does not permit quantitative analysis and serious interference problems may occur.ZusammenfassungDie Sekundärionen-Massenspektrometrie (Inonenstrahlmikroanalyse) ist eine neue Methode zur physikalischen Analyse in der Biologie. Die verwendete Apparatur (CAMECA SMI 300) ermöglicht Bilder von der Verteilung bestimmter Elemente mit einer Auflösung von 1 μm. Konzentrationen unter 1 p.p.m. sind bei den meisten Elementen noch wahrnehmbar.Es wird über die ersten Resultate an menschlichen Hautschnitten berichtet. Die in der normalen Haut vorkommenden Elemente zeigen keine besondere Anhäufung. Ein fremdes Element in der Haut ist leicht zu entdecken. Die Verteilung in der Epidermis von verschiedenen, lokal aufgetragenen klinischen Antiseptica wird gezeigt.Verglichen mit der Röntgenstrahlen-Mikroanalyse hat diese Methode den Vorteil ihrer Empfindlichkeit und die Möglichkeit, leichte Elemente zu bestimmen. Ihre Anwendung bei Hautpenetrationsstudien ist dennoch begrenzt, da sie keine quantitative Analyse erlaubt und Überlagerungsprobleme mit einschließt.