Pemphigus foliaceus antibodies and a monoclonal antibody to desmoglein I demonstrate stratified squamous epithelial-specific epitopes of desmosomes.

Pemphigus foliaceus (PF) is a human autoimmune disease in which autoantibodies are directed against the cell surface of epidermal cells. Using an immunoblotting technique, we recently demonstrated that a subgroup of PF patients have autoantibodies to the desmosomal core glycoprotein, desmoglein I (DGI). There are desmosomes in all epithelia and in heart, yet PF affects only stratified squamous epithelia. One explanation for this finding might be that there are tissue-specific differences in desmosomes. Thus, to determine whether certain epitopes of DGI are tissue-restricted, we performed immunofluorescence studies on various monkey tissues with the following antibodies: a rabbit polyclonal antiserum against whole desmosomes, which demonstrated the desmosomes in all tissues tested; a mouse monoclonal antibody against DGI, MmDGI-1; and PF sera that bound DGI on immunoblotting (PF IB+). In addition, we tested the tissues with PF sera that did not bind DGI by immunoblotting (PF IB-) to determine if these sera were different from PF IB+ sera in their tissue specificity. PF IB+, PF IB-, and MmDGI-1 antibodies stained all stratified squamous epithelia tested, including skin, tongue, upper esophagus, conjunctiva, and cornea; however, they did not stain heart or any nonstratified squamous epithelia, including gall bladder, small intestine, liver, ureter, and bladder. These results indicate that there is tissue heterogeneity of desmosomes, and that epitopes on DGI defined by both PF antibodies and a monoclonal antibody are present only in stratified squamous epithelia. In addition, PF IB- sera had the same tissue specificity as PF IB+ sera. These results may partially explain why PF involves only stratified squamous epithelia.