I test ELISA potrebbero essere utilizzati al posto del metodo di immunofluorescenza indiretta nella diagnosi delle dermatosi bollose autoimmuni?

Autoimmune bullous dermatoses (AIBD) comprise a heterogeneous group of organ-specific autoimmune disorders affecting the skin and mucous membranes, in which loss of adhesion between keratinocytes or between keratinocytes and basement membrane results in blister formation. They are characterized by an autoantibody response directed against structural proteins involved in the mechanisms of intercellular adhesion of the epidermis with the formation of an intraepidermal blister, in diseases of the pemphigus group, and against structural proteins of the dermo-epidermal junction with the formation of a subepidermal blister, in diseases of the pemphigoid group. Today, the diagnostic gold standard still remains the evidence of the presence, in the biopsy of skin and/or mucosa, of tissue autoantibodies adhering to the surface of the skin and mucosal structures, through the microscopic technique of direct immunofluorescence. Circulating autoantibodies, on the other hand, can be detected more easily in serum samples with the indirect immunofluorescence (IFI) method on monkey or rat tissues. The continuous progress made in the molecular identification of the antigenic targets of the autoantibodies of bullous dermatoses has led in the last twenty years to the development of new ELISA diagnostic systems that use recombinant fragments or entire protein domains of desmoglein1 (Dsg1), desmoglein3 (Dsg3), BP180, BP230, collagen VII, envoplaquin. The ELISA methods based on specific antigens, have today largely replaced the immunoblotting and immunoprecipitation methods, technically more demanding and too long in terms of response times, becoming the most used diagnostic tools in laboratories for the detection of specific circulating autoantibodies. It is however conceivable that the IIF, traditionally used as a screening method, will give way to ELISA methods as a first level test, due to the characteristics of objectivity in the interpretation of the result and greater standardization. The purpose of this review was to answer the following questions: What is the diagnostic accuracy of ELISA methods in the diagnosis of autoimmune bullous dermatoses? Can ELISA quantitative tests be used instead of the IIF? Literature data show a greater sensitivity of ELISA compared to the IIF method for the detection of anti-BP180 and BP230 autoantibodies in the diagnosis of diseases of the bullous pemphigoid group. As regards the pemphigus group, the data on the sensitivity of the IIF method range from 74% to 99.9% and are equal or lower than the analytical sensitivity of the ELISA methods for the determination of autoantibodies against Dsg1 and Dsg3. In conclusion, commercially available ELISA tests for the detection of antiskin autoantibodies have shown a high diagnostic specificity and sensitivity in patients with autoimmune bullous dermatoses comparable to the IIF method. Therefore, a possible diagnostic algorithm has been proposed.