Characterization of IgE-reactive autoantigens in atopic dermatitis - 1. Subcellular distribution and tissue-specific expression

We have previously reported that patients suffering from atopic dermatitis (AD) frequently display IgE autoantibody reactivity to human proteins expre ssed in cell lines of different histogenetic origins. Molecular cloning and in situ staining experiments revealed that certain IgE-reactive autoantige ns were expressed preferentially in target organs of atopy while others cou ld be detected in various tissues and cell types. Here we use serum IgE fro m AD patients to investigate the distribution of autoantigens in subcellula r fractions of the human epithelial cell line A431 and in human tissue spec imens. Results obtained showed that IgE-reactive autoantigens can be detect ed in the nuclear > microsomal > mitochondrial > cytoplasmic fraction of A4 31 cells as well as in a variety of human tissue specimens (brain, bone, in testine, liver, lung, muscle, skin, uterus) and effector cells of atopy (ba sophils, mast cells, T cells). If IgE autoreactivity plays a pathogenetic r ole in severe forms of atopy, organ-specific manifestations (e,g. AD) may r esult from the transport to and deposition of IgE-reactive autoantigens in certain target organs (skin) rather than from a preferential expression of the autoantigens in the affected tissues.