We hope future studies will reveal any potential positive or negative effects. We plan to use several animal models to address these questions.

In addition to the physical contact, it surprised us to find that these immune cells also have machinery to take up serotonin and to secrete it in an excitatory manner. The point behind this transmission is not entirely clear, but it appears to be an additional way of stimulating a T cell response.

The novelty is that we reveal a potential communication, involving the transmitter serotonin, between immune cells that is normally only found between neurons.

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.

The wider health implication is that commonly used SSRI antidepressants, which target the uptake of serotonin into neurons, may also impact the uptake in immune cells.

What I've tried to tell them is that it's an acknowledgement of their hard work, but not to let it go to their heads. They still have to go out and work hard every single day in order to maintain it.