Screening and analysis of adsorbents for pemphigus autoantibodies

Pemphigus represents a potentially life-threatening, blistering, chronic autoimmune disease involved with autoantibodies against desmosomal adhesion proteins, desmoglein 1 (Dsg1) and desmoglein 3 (Dsg3). These autoantibodies belong to biased immunoglobulin subclasses, predominantly IgG1 and IgG4. Although plasmapheresis is established for the treatment of pemphigus, specific immunoadsorption of the autoantibodies has not been clinically applied. In order to search for a novel adsorbent for the pemphigus autoantibodies, we screened a library of 26 chemical ligand adsorbents using the effluent of double filtration plasmapheresis obtained from pemphigus patients. As a result of the screening, we found that each adsorbent whose ligand is 2-thiophene ethylamine, tryptophan, para-guanidinophenylalanine, phenylalanine, or thienylglycine adsorb both antibodies to Dsg3 and Dsg1 efficiently, in that order. Furthermore, the thiophene adsorbent exhibited a high affinity for the IgG4 subclass. These results suggest that the thiophene adsorbent may be suitable for pemphigus immunoadsorption. Further in vivo animal studies and clinical trials are needed.