# Factors associated with non-pathogenic antibodies against desmoglein-3 in pemphigus foliaceus

## TL;DR

This study explores why some patients with pemphigus foliaceus have non-harmful antibodies against desmoglein-3, comparing them to other pemphigus types.

## Contribution

Identifies factors distinguishing non-pathogenic anti-Dsg3 antibodies in pemphigus foliaceus from pathogenic ones in pemphigus vulgaris.

## Key findings

- Anti-Dsg3 antibodies in PF are linked to older age and generalized disease form.
- Low anti-Dsg3 titers and lack of Dsg3 internalization suggest non-pathogenicity.
- HLA-DRB1 alleles associated with PF, not PV, were found in PF-anti-Dsg3+ patients.

## Abstract

Anti-desmoglein (Dsg)1 is produced in pemphigus foliaceus (PF), affecting exclusively the skin. Pemphigus vulgaris (PV) shows the production of anti-Dsg3 in the mucosal form, and anti-Dsg1 and 3 in the mucocutaneous form. Anti-Dsg3 autoantibodies have been rarely reported in PF.

To determine the factors associated with the production and pathogenicity of anti-Dsg3 in PF.

Comparative analytical study of three patients groups: 16 PF-anti-Dsg3+, and 42 PF-anti-Dsg3(-) and 22 PV treatment-naïve cases. Serum was used in the anti-Dsg1 and 3 ELISA, and in immunoblotting (IB) with human epidermis extract. The expression of Dsg1 and 3 in paraffin sections was analyzed by immunohistochemistry (IHC). HLA-DRB1 alleles were compiled from a database.

In the PF-anti-Dsg3+ group: age range similar to that of the PV group (p > 0.9999); predominance of the generalized form of PF (p = 0.002); anti-Dsg3 titers lower than those of PV (p < 0.0001); IB confirmed Dsg3 identification in one (8.33%) of 12 patients; IHC showed exclusive cytoplasmic internalization of Dsg1; HLA-DRB1 alleles of susceptibility to PF, with the absence of alleles associated with PV, in the five typed patients.

Most of the patients in the PF-anti-Dsg3+ group were undergoing treatment.

The presence of anti-Dsg3 antibodies in PF was related to older age (comparable to that of PV) and the generalized form of PF. The non-pathogenicity of anti-Dsg3 antibodies in PF can be attributed to the low serum anti-Dsg3 titers, the lack of Dsg3 internalization as detected by IHC, and the absence of PV-associated HLA-DRB1 alleles.