Levels of anti-BP180 NC16A IgE do not correlate with severity of disease in the early stages of bullous pemphigoid

Bullous pemphigoid (BP), a common autoimmune skin disease, is associated with IgG autoantibodies against the hemidesmosomal proteins, BP180 and BP230. In addition to IgG, IgE has been shown to play a role in the disease. However, the association between disease activity and IgE specific to the NC16A domain of BP180 in blister fluid remains unclear. Our objective was to evaluate the correlation between BP disease activity and BP180 NC16A-specific IgE sera and blister fluid titers, and to analyze changes during treatment. We evaluated the levels of anti-BP180 IgE autoantibodies in the sera and blister fluids of 37 BP patients using an Enzyme-linked immunosorbent assay. We also observed changes in the levels of these antibodies in 2 BP patients at 4 or 5 different time points (day 0 when the patient first visited our hospital, day 5, day 14, day 39 and day 62 for patient 1; day 0, day 4, day 8 and day 17 for patient 2). We also collected extra serum samples from the 2 patients when the disease was controlled (blister disappeared) (day 85, day 104 and day 146 for patient 1 and day 123, day 158 and day 189 for the other patient). IgE anti-BP180 antibodies were detected in the serum of 72.97 % of the patients. There was no correlation between disease activity scores and BP180 NC16A IgE titers in serum (r = -0.077, p > 0.05) or in blister fluid (r = 0.262, p > 0.05). The levels of the autoantibody in serum were positively correlated with that in blister fluid (r = 0.6651, p < 0.001); however, the levels continued to rise despite effective control of the disease in the initial two to 6 weeks of diagnosis. The level of this autoantibody reached a peak on day 39 for patient 1 and on day 17 for patient 2 although the systemic and topical medication of steroid had controlled the disease process effectively. We conclude that levels of anti-BP180 NC16A IgE are higher in the sera than blister fluids. These levels could generally reflect disease severity throughout the course of the disease, but not in the early stages of medication.