Cloning and identification of autoantigens

Autoantigens are well-conserved, generally intracytoplasmic antigens that are recognized by autoantibodies and/or self-reactive T cells. Until relatively recently, the molecular identities of the autoantigens have remained elusive; the application of recombinant DNA technology has dramatically changed this picture. Here, we focus on two generic methodologies that have been used successfully to clone autoantigens: (1) hybridization screening of cDNA libraries by labeled DNA probes and (2) immunoscreening of expression cDNA libraries. The potential applications and usage of the polymerase chain reaction in the cloning of autoantigens are also discussed. The clones that have been studied are subsequently subcloned onto plasmid vectors and expressed in Escherichia coli. The biochemical identification of autoantigens has been based on nucleotide sequencing data, biochemical activities, and epitope mapping.