Expression of 5‐HT_3Areceptors in cells of the immune system

There is evidence from both human and animal research that 5-hydroxytryptamine3 (5-HT3) receptor antagonists, particularly tropisetron, exert analgesic and antiinflammatory effects. However, the underlying mechanisms of these effects including the expression of 5-HT3 receptors in cells of the immune system have not yet been investigated in detail. Therefore, we investigated the expression of the 5-HT3A receptor in primary human monocytes, chondrocytes, T-cells, dendritic cells, and synovial tissue. We found that 5-HT3A receptors are expressed in monocytes, chondrocytes, T-cells, and synovial tissue but not in dendritic cells. Our data show that 5-HT3A receptors are widely expressed in cells of the immune system and that they might play an important role in inflammatory events and in the observed antiphlogistic effects of 5-HT3 receptor antagonists.