Scientists find connection between nerve cells and immune system

A direct connection exists between the brain and the immune system – at least in mice. Scientists at the Helmholtz Centre for Infection Research in Braunschweig conducted a comprehensive study of mice intestine and the surrounding blood and lymph vessels using special microscopy and marking techniques.

What they found: numerous immune cells imbedded in the tissue around the intestine are joined to nerve strands and cells. "We already have many indications that immune defenses are at least partially influenced by the nervous system," explains Helmholtz scientist Dr. Kurt Dittmar. "We have now seen these connections under the microscope." In all probability, says Dittmar, the situation in humans is not all that different to mice. The assumption is that the brain and psyche in mice have an effect on the immune system. "For many infectious diseases and autoimmune ailments," he says, "connections have been observed on a regular clinical basis between the psyche and the severity of an illness."

The Helmholtz researchers are not quite ready to speculate on the specific interactions at work. According to Dittmar, not enough is known about how the nervous system regulates immune defenses. "Research into the interactions involved is still in the early stages," he says, "but the cell connections studied could, in the near future, also lead to a better understanding of the paths of some infections, e.g. for prions that induce mad cow disease, which could enter the nervous system through the intestines."

In their research, the scientists used the techniques of histochemical immunology: antibodies that are produced against molecules on a cell surface that only appear on certain tissue types are marked with a specific dye. Different tissues take on a different color under a light microscope. "We have developed this method further," says Helmholtz guest researcher, Bin Ma, from China. "We can now characterize up to seven cell types simultaneously in histological cross-sections and, so far, we have made visible an astounding number of contacts between immune and nerve cells." These include some of the most important immune cell types, such as B-lymphocytes, T-lymphocytes and dendric cells – all of which form connections to the nerves. Furthermore, it has also been discovered that quite a few nerve strands end in lymph glands around the intestines, such as the so-called Peyer's patches, where immune cells gather. Researchers also found indications that immune cells can recognize transmitters, the messenger substances of the nervous system.