Antidepressants that work by manipulating serotonin levels in the brain may also affect the user's immune system in ways that are not yet understood, say researchers from the Georgetown University Medical Center. The researchers found that serotonin is passed between key cells in the immune system, and that serotonin activates an immune response in the body. But it is unclear at this point whether SSRI (selective serotonin reuptake inhibitors - drugs that include Prozac, Zoloft and Paxil) antidepressants have a beneficial or damaging effect on the human immune system. Georgetown researcher Gerard Ahern said that while it may be possible that SSRI drugs may restore a healthy immune function in people who are depressed and prone to infections, it is possible that they might also bolster immunity to the point that they trigger autoimmune disease. "At this point we just don't know how these drugs might affect immunity, so we really need to clarify the normal role of serotonin in immune cell functioning," he said.
The finding that serotonin is rapidly passed between immune cells in a manner similar to its transmission between brain neurons surprised the researchers, who revealed their findings in the journal Nature Reviews Immunology. "The novelty is that we reveal a potential communication, involving the transmitter serotonin, between immune cells that is normally only found between neurons," Ahern said.
The findings show that serotonin can quickly excite a T-cell response in the body. Antidepressants that block serotonin reuptake "likely change some of the parameters of T-cell activation, but we don't know yet if it enhances or inhibits the total immune response," Ahern said. "But it is something that should be explored because we really have no idea what SSRIs are doing to people's immune systems."
Source: Georgetown University Medical Center
