Dichotomy of Autoreactive Th1 and Th2 Cell Responses to Desmoglein 3 in Patients with Pemphigus Vulgaris (PV) and Healthy Carriers of PV-Associated HLA Class II Alleles

Abstract

Pemphigus vulgaris (PV) is the most severe autoimmune bullous skin disorder and is primarily associated with circulating autoantibodies (autoAb) against desmoglein 3 (Dsg3). In light of recent evidence that autoreactive T cells are critical for the induction and regulation of Ab production, the goal of this study was to characterize and quantitate autoreactive T cells in patients with PV and healthy controls. Peripheral Dsg3-reactive Th cells from 28 patients with acute-onset, chronic active, and remittent PV were quantitated by MACS secretion assay. Dsg3-reactive Th2 cells were detected at similar frequencies in all studied PV patients, while the number of autoreactive Th1 cells exceeded those of Th2 cells in chronic active PV. In contrast, healthy carriers of the PV-associated HLA class II alleles, DRB1*0402 and DQB1*0503, exhibited exclusively Dsg3-reactive Th1 cell responses, while healthy carriers of other HLA class II alleles did not. Moreover, the presence of IgG1 and IgG4 against Dsg3 was directly related to the ratio of Dsg3-reactive Th1/Th2 cells. T cell recognition of Dsg3 was restricted by HLA-DRB1*0402 and DQB1*0503 in PV patients and Dsg3-responsive healthy donors. These observations strongly suggest 1) that the appearance of Dsg3-reactive Th2 cells is restricted to patients with PV; 2) that specific HLA class II alleles that are prevalent in PV are critical for T cell recognition of Dsg3 in PV patients and Dsg3-responsive healthy donors; and 3) that autoAb production is associated with both Th1 and Th2 cells.

T Cell Recognition of Desmoglein 3 Peptides in Patients with Pemphigus Vulgaris and Healthy Individuals

“…Upon selection by MACS cytokine secretion assay, Dsg3-specific Th responses were not only detected in a cohort of PV patients (irrespective of their clinical status) but also in healthy carriers of the PV-associated HLA class II alleles, DRB1*0402 and DQB1*0503. This finding confirms previous studies from our group supporting the idea that carriers of distinct HLA class II alleles are genetically at risk to develop Dsg3-specific T cell responses independent from the development of PV (21,22).…”

“…5). These findings are consistent with epidemiological studies showing a strong association of PV with HLA-DRB1*0402 (16) and HLA-DQB1*0503 (17,18) and a recent study from our group that identified Th cell responses to Dsg3 not only in PV patients but also in healthy carriers of the aforementioned PV-associated HLA class II alleles (22). These findings are in line with three independent studies demonstrating that Dsg3-specific TCC were restricted by HLA-DRB1*0402 (19,20,43).…”

“…Patients with remittent PV had not experienced new mucosal blisters/erosions for 6 mo or more before the study. Some of the studied PV patients had been already included in a recent study (22). However, the Dsg3-specific TCC that were characterized in the present investigation were newly generated for this purpose.…”

“…In PV patients, both Dsg3-reactive Th1 and Th2 cells were identified that recognized portions of the ECD of Dsg3 in the context with PV-associated HLA class II alleles (20 -22). Autoreactive Th1 cells reactive to Dsg3 were also isolated from the blood of healthy carriers of the PV-associated HLA class II alleles, HLA-DRB1*0402 and DQB1*0503 (21,22).…”

“…For protein production, High-Five insect cells were inoculated for 4 days with the baculovirus at a multiplicity of infection of 10. Dsg3 protein was purified from culture supernatants by affinity chromatography over Ni-NTA-linked (nickel-nitrilotriacetic) agarose (Qiagen, Hilden, Germany) as recently described (22).…”