No abstract

Pemphigus vulgaris (PV) is a blistering skin disorder mediated by autoantibodies targeting the epidermal adhesion molecule desmoglein 3 (Dsg3). As Th2-associated cytokines are necessary for directing antibody production, it is hypothesized that Dsg3-specific Th2 activity is associated with active disease. We used cell-surface-matrix technology in combination with flow cytometry to characterize the Dsg3-reactive T-cell population using peripheral blood mononucleocytes sampled from PV patients stratified by active (n = 9) or remittent disease (n = 6), and healthy human leucocyte antigen-matched controls (n = 5). We evaluated interferon-gamma-producing CD4+ cells (Th1) and interleukin (IL)-10- or IL-4-producing CD4+ cells (Th2). The mean frequency of Th2 CD4+ T cells was significantly elevated for five of nine PV patients with active disease. No significant Th2 responses were detected for patients with remittent disease or controls. There was a significant association of Th2 activity with active disease compared with remittent and control groups (P = 0.026 and P =0.012, respectively), and Th2 activity was significantly correlated with anti-Dsg3 IgG titre (P = 0.044). One patient with remittent disease converted from a Th2-negative to a Th2-positive response with the initiation of disease activity. An antigen-specific CD4- lymphocyte response was detected in five PV patients (36%), and was shown to correlate closely with the CD8+ population. These results are consistent with the hypothesis that Th2 response directs autoantibody production and is therefore associated with disease activity in PV.

Early studies of genetic susceptibility to pemphigus vulgaris (PV) showed associations between human leukocyte antigen (HLA) DR4 and DR6 and disease. The emergence of DNA sequencing techniques has implicated numerous DRB1 and DQB1 loci in various populations, leading to confusion regarding which exact alleles confer susceptibility. The strong linkage disequilibrium among DR and DQ HLA alleles further complicates the investigation of the true susceptibility loci. In this study, we report genotyping data for the largest sampling of North American Caucasian nonJewish and Ashkenazi Jewish PV patients studied to date and compare our data with other population studies. To pinpoint true susceptibility, alleles among overrepresented sequences, we applied a step-wise reductionist analysis through (1) determination of the degree of linkage disequilibrium (LD) between purportedly associated alleles, (2) haplotype frequencies comparisons, and (3) primary sequence comparisons of disease-associated versus non-disease-associated alleles to identify crucial differences in amino acid residues in putative peptide binding pockets. Collectively, our data provide extended support for the hypothesis that the HLA associations in Caucasian PV patients map to DRB1*0402 and DQB1*0503 alone. Further structure-function studies will be required to define the exact mechanisms of HLA-mediated control of susceptibility and resistance to disease. Human Immunology 68, 630 -643 (2007).