Bead aggregation assays with desmoglein and desmocollin for the evaluation of disease activity in pemphigus.

BACKGROUND

Previously, we developed bead aggregation assays with recombinant desmoglein (Dsg) and desmocollin (Dsc) and found that pemphigus autoantibodies directly block the heterophilic trans-interaction of Dsg/Dsc.

OBJECTIVE

To investigate whether inhibitory activities measured by bead aggregation assays can be used to assess pemphigus disease activity.

METHODS

First, we investigated whether the inhibitory activity correlated with patients' clinical disease activity using sera of 21 pemphigus vulgaris (PV) and 16 pemphigus foliaceus (PF) cases at the time of initial diagnosis. Next, we investigated whether the inhibitory activities reflect disease activities along the time course.

RESULTS

The inhibitory activities were significantly correlated with the pemphigus disease area index (PDAI) (Spearman rank correlation, 0.761, n = 21, p < 0.01) in the PV group. However, no significant correlation was observed between Dsg3 ELISA titers and PDAI (Spearman rank correlation, 0.238, p > 0.05). Similar results were observed in the PF group (0.746, p < 0.01 vs. 0.357, p > 0.05). The inhibitory activities were evaluated using sera from the initial onset, remission, and relapse stages for four PV and four PF cases. The inhibitory activity changed in parallel with the clinical disease activity in seven out of eight cases. In two cases, the inhibitory activity correlated more accurately with disease activity than the Dsg ELISA titers.

CONCLUSIONS

Bead assay is useful for assessing disease activity in patients with pemphigus. Furthermore, our findings suggest that the direct inhibition of Dsg/Dsc adhesion is important for pemphigus pathogenesis.