Bullous Pemphigoid Anti-BP180-NC16A Autoantibody Reactivity in Healthy Individuals is Associated with Marked Hypovitaminosis D and Th2-like Cytokine Predominance

Autoimmune bullous disease autoantibodies, particularly including bullous pemphigoid (BP)-related anti-BP180-NC16A IgG, have been reported in a small subset of healthy individuals, but information about associated factors is lacking. We hypothesized that an abnormal status of immunomodulatory vitamin D could play a role in anti-BP180-NC16A autoantibody reactivity in healthy persons. In addition, we aimed to evaluate the cytokine profile associated with these autoantibodies. Plasma samples from 34 anti-BP180-NC16A IgG-reactive and 85 anti-BP180-NC16A IgG-negative healthy blood donors were tested for levels of 25-hydroxyvitamin D [25(OH)D] and a wide range of cytokines (IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, IL-17A, IL-17F, IL-21, IL-22, IFN-γ, and TNF-α). We observed that anti-BP180-NC16A IgG-reactive healthy subjects had significantly lower plasma 25(OH)D levels and about a two-fold higher rate of vitamin D deficiency (< 20 ng/ml) compared to anti-BP180-NC16A IgG-negative healthy persons. In addition, anti-BP180-NC16A IgG-positive samples were characterized by significantly higher levels of IL-2, IL-5, IL-9, IL-10, and IL-13 which were, however, not significantly associated with the vitamin D levels. Our results indicate that healthy individuals with BP autoantibody reactivity share similarities with BP patients regarding the vitamin D status and cytokine profile (i.e., marked hypovitaminosis D and Th2 predominance), which may have pathophysiologic implications.