Immune-mediated subepithelial blistering diseases of the mucous membranes. Improving the detection of circulating autoantibodies by the use of concentrated serum samples.

ABSTRACT

BACKGROUND AND DESIGN: Comparison of detection of circulating autoantibodies before and after concentration of serum samples from patients with suspected immune-mediated subepithelial blistering diseases of the mucous membranes. We determine whether the use of concentrated serum samples from patients with suspected immune-mediated subepithelial blistering diseases of the mucous membranes improves diagnostic sensitivity for circulating antibodies. We studied 13 patients from a university-based referral practice who had no skin lesions and a scarring subepithelial blistering disease of the mucous membranes. Three of these patients had detectable circulating autoantibodies and 10 had negative indirect immunofluorescence study results using standard techniques. The main outcome measures after concentration of serum samples were detection of circulating autoantibodies on salt-split skin by indirect immunofluorescence, immunoblotting, and immunoprecipitation. RESULTS: Of the 10 patients in whom circulating autoantibodies had not been detectable with standard techniques, circulating IgG antibodies were detected in 5 (50%) and circulating IgA antibodies in 3 (30%). Of the 3 patients in whom circulating autoantibodies had been detectable with standard techniques, 1 (33%) had circulating IgA antibodies that immunoblotted the 97-kd linear IgA bullous disease antigen only when concentrated serum samples were used. CONCLUSIONS: The use of concentrated serum samples can improve our ability to detect the presence and antigenic specificity of circulating autoantibodies in patients with suspected but unclassifiable immune-mediated subepithelial blistering diseases of the mucous membranes.