Type I allergy is a genetically determined disorder that leads to the formation of immunoglobulin E, or IgE, antibodies against otherwise innocuous environmental particles. These allergenic particles bind to IgE and induce cross-linking on IgE receptor-bearing mast cells and basophils, which then rapidly release anaphylactic mediators such as leukotrienes and histamine. In some atopic dermatitis (AD) patients, reactivity is also directed to self or autoantigens.
By screening an epithelial cell expression cDNA library with serum IgE from AD patients, Natter et al. (1998) identified a cDNA encoding a deduced 313-amino acid protein, CBARA1, which they called ARACALC (atopy-related IgE autoantigen with a calcium-binding domain). Northern blot analysis detected 1.8- and 3.5-kb CBARA1 transcripts in an epithelial cell line but not in endothelial cells. Immunoblot analysis showed reactivity of AD sera but not systemic lupus erythematosus sera with CBARA1.