Characterization of peripheral benzodiazepine receptors in human blood mononuclear cells.

In the present study, peripheral-type benzodiazepine receptors in human circulating mononuclear cells were characterized, using [3H]PK 11195 as specific ligand. The specific binding was saturable, with a Bmax of 14 pmol/mg protein and a Kd of 7 nM. The pharmacological characterization, using different displacing drugs, indicated a mitochondrial type of peripheral benzodiazepine receptor since it was not coupled to the GABA receptor and was displaced by protoporphyrin IX. These data indicate that human circulating mononuclear cells possess benzodiazepine recognition sites, similar to non-neuronal receptors. The role of these receptors and possible modifications in different diseases need to be investigated.