Pivotal Role of Lesional and Perilesional T/B Lymphocytes in Pemphigus Pathogenesis

Pemphigus is a skin and mucosal membrane-targeting autoimmune bullous disease. Previous studies have shown that circulating anti-desmoglein1/3 antibodies are pathogenic and mediate blister formation. However, the role of infiltrating immune cells in lesional skin has not been fully investigated. In this study we showed that there existed a large number of B and T lymphocytes and plasma cells in the skin lesions by immunohistochemistry and immunofluorescence staining. In addition, a significantly increased number of Dsg1- and Dsg3-specific B cells could be identified by flow cytometric analysis or enzyme-linked immunospot technique (i.e., ELISPOT) assay. Furthermore, anti-Dsg1 and Dsg3 antibodies could be detected from the supernatant of in vitro cultures with isolated lymphocytes from lesional skin. We found that most T lymphocytes infiltrating pemphigus vulgaris lesions were CD4⁺ T helper cells expressing IL-21 and IL-17a but not typical T follicular helper cells expressing CXCR5. Additionally, our microarray assay showed that the level of chemokine CCL19 was significantly elevated, suggesting active T-/B-lymphocyte trafficking and aggregation in the pemphigus vulgaris lesions. Collectively, our results suggest a critical role of locally infiltrating lymphocytes in pemphigus pathogenesis.