A new recombinant designer antigen for autoantibody diagnostics in patients with bullous pemphigoid has been developed in a collaboration involving a substantial contribution from EUROIMMUN researchers. The new protein is much better suited for diagnostic purposes than the natural version. From the huge BP180 molecule it contains only the pathogenetically relevant target structure – the NC16A domain, and this as a tetramer (NC16A-4X*). On the basis of this antigenic work of art an extremely efficient ELISA test system has been developed, which exhibits a sensitivity of 90% (!) (specificity 98%!) and detects 100% of patients with gestational pemphigoid. If autoantibodies against BP230 are additionally determined, 93% of patients with bullous pemphigoid can be identified serologically.

In pemphigus foliaceus and pemphigus vulgaris autoantibodies against desmosomes are investigated. The main target antigens are the desmogleins (Dsg) 1 and 3. In pemphigus foliaceus only Dsg 1 reacts, while in pemphigus vulgaris a reaction occurs with either Dsg3 alone or Dsg1 and Dsg3 together. For this application the use of recombinant antigens is state-of-the-art. These are synthesised at EUROIMMUN in human cell lines, in which they undergo species-faithful and thus authentic posttranslational modification. The corresponding state-of-the-art ELISAs show impressive sensitivities of 96.0% (Dsg1) and 100% (Dsg3) at specificities of 99.1% (Dsg1) and 99.6% (Dsg3).

All of these autoantibodies can also be detected by indirect immunofluorescence. Up until now the standard substrate has been tissue sections of oesophagus and tongue. However, with these substrates it is difficult to distinguish between Dsg1 and Dsg3, and patterns are often obscured due to unspecific reactions (e.g. from antibodies against keratin). Today a powerful Mosaic of specific transfected cells together with the tissue sections allows reliable diagnosis with a single test.

The test kits are equally suited to primary diagnostics, disease course assessment and therapy monitoring. The ELISAs demonstrate the following characteristics:

• CE conformative standard curve using 3 calibrators
• Positive and negative controls included in test kit
• Wide measurement range (2-200 RU/ml)
• Short, standard incubation times (30 min/30 min/15 min)
• Reagents exchangeable with those in other EUROIMMUN ELISAs
• Attractive price