A simple method for elution of IgA deposits from the skin of patients with dermatitis herpetiformis

To better understand the role of autoimmunity in the pathogenesis of dermatitis herpetiformis, linear IgA bullous dermatosis or other skin disorders, the antigenic specificity of the immune reactants bound in vivo in the skin must be identified. In order to do so, one must first be able to elute these immune reactants from the skin. We describe here a simple method of eluting not only specifically bound IgG, but also IgA and other immunoglobulins and complement components from skin biopsy material. The method involves cutaneous washing of the entrapped serum proteins in PBS pH 7 and pH 5 buffers followed by specific immunoglobulin elutions at pH 3 and 2. The IgA deposits which could not be removed by this treatment were eluted by a combination of low pH (0.5 M citrate pH 2) and a chaotropic agent (2 M NaCl). The relative concentration of IgA in eluates when quantitated by fluoroimmunoassay were three-to five-fold higher in dermatitis herpetiformis skin biopsy specimens, than in eluates of bullous pemphigoid or normal skin biopsy specimens.