Brain-like activity in immune system found!

Researchers show for the first time that human immune cells contain particles that have neurotransmitters including dopamine, which plays a crucial role in immune responses.

"These particles were previously thought to only exist in neurons in the brain and we think they are, potentially, an excellent target for therapies to speed up or dampen the body's immune response, depending on the disease you're dealing with," said the author.

Neurons rely on synaptic interactions and neurotransmitters such as dopamine, which are small molecules transmitted across synapses to deliver signals from one cell to another that play a major role in reward-motivated behavior.

Authors show that a proportion of human T_FH cells contain dense-core granules marked by chromogranin B, which are normally found in neuronal presynaptic terminals storing catecholamines such as dopamine. T_FH cells produce high amounts of dopamine and release it upon cognate interaction with B cells.

"Like neurons, specialised T cells transfer dopamine to B cells that provides additional 'motivation' for B cells to produce the best antibodies they can to help to clear up an infection," author said.

"The human body has developed an advanced form of protection against bacteria, viruses and other foreign bodies that relies on the immune system.

"Immune responses are essential for recognizing and defending humans against substances that appear foreign and harmful to the individual."

Dopamine causes rapid translocation of intracellular ICOSL (inducible T-cell co-stimulator ligand, also known as ICOSLG) to the B-cell surface, which enhances accumulation of CD40L and chromogranin B granules at the human T_FHcell synapse and increases the synapse area.

The researchers analyzed around 200 tissue samples from children who had their tonsils removed, observing the transfer of dopamine from specialized T cells to B cells through a synaptic interaction.
They also worked with a mathematician to model the immune system's brain-like activity in a human in response to vaccines.