Palm tissue displaying a polyclonal autoimmune response in patients affected by a new variant of endemic pemphigus foliaceus in Colombia, South America.

We previously described a new variant of endemic pemphigus foliaceus in El Bagre, Colombia, South America (El Bagre-EPF). On physical examination, the palms and soles of El Bagre-EPF patients reveal an edematous texture and mild hyperkeratosis, in comparison with the non-glabrous skin of the patients where blisters, pustules or other lesions are commonly found. Based on the preceding observation, we tested the palms of 20 El Bagre-EPF cases and 20 controls from the endemic area for any pathological alterations in the samples by direct immunofluorescence (DIF). Our DIF demonstrated pathological deposits of fibrinogen and albumin, as well as IgG, IgA, IgM, IgD and C3c, at 1) the epidermal basement membrane zone; 2) around isolated areas in the epidermis, 3) within the dermal vessels and nerves, and 4) in areas surrounding dermal neurovascular structures and sweat glands. Specific markers for blood vessels, including 1) anti-intercellular adhesion molecule 1 (ICAM-1)/CD54, and 2) anti-junctional adhesion molecule (JAM-A); as well as specific markers for nerves, including 1) anti-glial fibrillary acidic protein (GFAP), and 2) anti-human neuron specific enolase (NSE) co-localized with the patients' autoantibodies. Although no blisters, ulcerations, pustules or erosions are clinically observed on the palms of El Bagre-EPF patients, our DIF detected distinct immunoreactivity in palm tissue. These alterations may contribute to the clinically edematous texture of the palms and the mild clinical hyperkeratosis found in most of these patients. We propose that normal glabrous skin and non-glabrous skin may be different with regard to the expression of selected molecules, which may vary in number, size or structural organization depending on their anatomical site. Our findings may also partially explain the hyperkeratotic palms that have been clinically well documented in the chronic phase of fogo selvagem i.e., endemic pemphigus foliaceus, in Brazil.