This work employs an
epitope mapping of
carbonic anhydrase (CA),
isoform I (CA I), for detection of the main
immunodominant epitopes. Our interest has arisen from an observed spontaneous
tumor regression in patients who developed an
aplastic anemia type syndrome after a high-dose
therapy with autologous
stem cell transplantation and whose sera contained high titer of anti
carbonic anhydrase (anti-CA)
autoantibodies. There are many indications that the presence of these
autoantibodies may provide significant survival benefit for the patients. Western blot analysis confirmed strong immunoreactivity of the patients' sera with several CA
isoforms and the CA I has been selected for our study as a highly abundant and widely distributed
isoform. The applied analytical approach consists of specific fragmentation of CA I
protein followed by immunospecific isolation of
peptides reacting with polyclonal anti-CA I
autoantibodies of patients in spontaneous remission. We improved the standard
epitope mapping schema by incorporating the benefits of magnetic carriers and biomagnetic separation techniques. Mass spectrometry has been applied for detection and identification of
epitopes and the acquired results were verified by bioinformatic tools. The candidate
epitopes of CA I (NVGHS, DGLAV, SSEQL, and SLKPI) are discussed herein as potential therapeutic targets. This work highlights the usefulness of the
epitope mapping technique based on magnetic
microspheres for effective and rapid determination of
immunodominant epitopes of the target
protein.