Use of 1M NaCl split skin in the indirect immunofluorescence of the linear IgA bullous dermatoses.

We compared 1M NaCl split skin with intact skin as substrates for detection of circulating IgA anti-basement membrane (BMZ) antibodies in linear IgA dermatosis (LAD). The sera of 63 patients with LAD including 27 adults and 36 with chronic bullous dermatosis of childhood (CBDC) were examined. 62% of patients overall had circulating IgA anti-BMZ antibodies detectable on intact skin. 73% of patients had circulating antibodies detectable on 1M NaCl split skin as an additional 7 sera were positive. This was a statistically significant increase (p less than 0.01). The sera were mostly positive at a higher titre on the split skin when compared with intact skin. On routine indirect immunofluorescence (IIF) all positive sera produced linear fluorescence on the epidermal side of the split. Twenty serum samples were incubated with split skin overnight; 4 of these specimens exhibited linear fluorescence on the epidermal and dermal sides of the split after this prolonged incubation. These findings suggest that 1M NaCl split skin is a more sensitive substrate for detection of circulating IgA anti-BMZ antibodies in LAD, that these antibodies are heterogeneous and that the target antigen has an epidermal component.