Production of an agonist-like monoclonal antibody to the human A2A receptor of adenosine for clinical use

The second extracellular loop of the A2A receptor (A2AR) of adenosine was used to immunize mice for production of Adonis, an IgM monoclonal antibody. Adonis bound to the immunogen peptide and the native receptor in ELISA with KD values in 6.51–12.35 nM range. It recognized a linear epitope of 7 amino acids (LFEDVVP) at the C-terminal part of the external loop. Adonis revealed a 45-kDa band in lysate of human peripheral blood mononuclear cells in Western blotting in denaturing conditions. This served to monitor the up-regulation of the A2AR expression by caffeine. Adonis stimulated the cAMP production and inhibited the cell proliferation of an A2AR transfected stable cell line. These results confirm the immunogenicity and the functional relevance of the second extracellular loop of the A2AR. They suggest that Adonis may be of clinical use in various pathological situations to measure the regulation of the A2AR expression and to act as A2AR agonist drug.