Dopamine receptors on human T- and B-lymphocytes

Abstract

The presence of functional dopamine receptors on differentiated cells of the mammalian immune system is still under discussion. This study has utilized (-)-[ 3H]sulpride as a ligand to detect the presence of recognition sites of the dopamine D 2 receptor family on human T- and B-lymphocytes. The (-)-[ 3H]sulpiride binding was of high affinity ( K d 0.9 nM ± 0.2 nM, specific, saturable ( B max 10.2 ± 1.4 fmol/10 6 cells) and reversible. The pharmacological characterization of the recognition site suggests, similarities mainly with the D 2 and D 4 rather than D 3 subtype of dopamine receptor. Furthermore, dopamine treatment was able to reduce the intracellular cAMP levels of lymphocytes stimulated with forskolin, thus suggesting a potential functional significance of this dopamine receptor in mediating neural-immune interactions.