HLA-DPDQDR is expressed in all lesional skin from patients with autoimmune skin diseases

Abstract

Introduction: Human genes responsible for human antigen presentation and transplant rejection functions are located on the short arm of Chromosome 6, and are called the Major Histocompatibility Complex (MHC). Moreover, the primary physiologic function of MHC molecules is to present peptides to T lymphocytes. MHC molecules are integral components of the ligands that most T cells recognize, since the T cell receptor (TCR) has specificity for complexes of foreign antigenic peptides, as well as self-MHC molecules. Aim: Our investigation attempts to investigate the presence of HLA-DPDQDR within lesional skin biopsies from patients affected by autoimmune skin blistering diseases (ABDs). Materials and Methods: We utilized immunohistochemistry (IHC) to evaluate the presence of HLA-DPDQDR in lesional skin biopsies of patients affected by ABDs. We tested 30 patients with endemic pemphigus foliaceus (EPF), 15 controls from the EPF endemic area, and 15 biopsies from healthy controls from the USA. We also tested archival biopsies from patients with selected ABDs, including 30 patients with bullous pemphigoid (BP), 20 with pemphigus vulgaris (PV), 8 with pemphigus foliaceus (PF), 14 with dermatitis herpetiformis (DH) and 2 with epidermolysis bullosa acquisita (EBA). Results: Most ABD biopsies stained positive for HLA-DPDQDR in the lesional blisters and/or inflamed neurovascular neuroplexus areas in the superficial dermis, and also at mesenchymal-endothelial like-cell junctions in the dermis. In BP, EBA and EPF, the HLA-DPDQDR staining was also seen in dermal eccrine sweat gland coils and ducts. Conclusion: We document that HLA-DPDQDR is expressed in several anatomic areas of lesional skin in patients with ABDs. Notably, HLADPDQDR positivity was also consistently present in areas of the classic immune response, including epidermal intercellular junctions in pemphigus, and at basement membrane sites in bullous pemphigoid and other subepidermal blistering diseases.