Human desmocollin 1a transiently expressed in COS-7 cells and NIH 3T3-3 cells is reacted by IgG4 antibodies in a pemphigus foliaceus serum.

Human desmocollin (Dsc) 1 is an autoantigen in the subcorneal pustular dermatosis type of IgA pemphigus. Moreover, Dscs, particularly bovine Dscs, are recognized by IgG antibodies in certain sera of various types of pemphigus by immunoblotting. In this study, 10 pemphigus sera were examined by immunofluorescence for IgG antibodies to human Dsc1a, Dsc2a and Dsc3a transiently expressed in COS-7 and NIH 3T3-3 cells using two different transfection methods. IgG antibodies in a number of sera showed a strong background staining with untransfected COS-7 and NIH 3T3-3 cells. Using COS-7 cells, a pemphigus foliaceus serum, which did not stain untransfected COS-7 cells, was found to contain IgG antibodies reactive exclusively with Dsc1a. This serum showed the same reactivity in studies using NIH 3T3-3 cells. Moreover, this pemphigus foliaceus serum contained IgG4, but not IgG1 antibodies, to Dscla expressed in the NIH 3T3-3 cells. These results indicate that autoantibody response in pemphigus foliaceus might be more heterogenous than hitherto supposed.