Individual organs capable of independent immune response, study suggests

Wednesday, December 19, 2012 by: David Gutierrez, staff writer
Tags: organs, immune response, infectious disease

(NaturalNews) Individual organs may possess innate, individual immune systems separate from the body's larger immune system, suggests a study conducted by researchers from The Rockefeller University, Harvard Medical School and the Memorial Sloan-Kettering Cancer Institute.

To date, models of the immune system have focused on actors such as white blood cells, which are produced by blood marrow and circulate through the body and circulate through the body searching out and destroying infectious agents and other health threats. But the new study found that the brain is capable of mounting a response to destroy certain viruses without involving white blood cells, or any other component of what is typically thought of as the "immune system."

The study came out of prior research by scientists at The Rockefeller University into children with a disease called Herpes simplex encephalitis, a potentially fatal brain infection caused by the herpes virus HSV-1. The researchers had previously determined that these children possess a genetic defect leading to faulty function of the immune system agent known as toll-like receptor 3 (TLR3).

TLR3 function as both a pathogen detector and an immune trigger. After detecting an infection, the receptor causes surrounding cells to release proteins called interferons, which hamper the pathogen's ability to reproduce.

But the researchers found that the mutation in children with Herpes simplex encephalitis did not appear to affect TLR3's effect on white blood cells, which has been the most well-studied.

"One interesting thing about these patients is that they didn't have any of the other, more common herpes symptoms," Zhang said. "They didn't have an infection on their skin or their mouths, just in their brains. We therefore hypothesized that the TLR3 response must be specifically responsible for keeping the herpes virus from infecting the brain and not necessary in other parts of the body."

Intrinsic immunity

To test their idea, the researchers induced stem cells made from the tissue of patients with Herpes simplex encephalitis to develop into central nervous cells. They then exposed these cells to HSV-1 and to a synthetic RNA mimicking a byproduct of the virus' reproduction. The researchers then measured levels of interferons, concluding that levels were indeed lower than they should be - suggesting a faulty FLR3 response. But when the same virus and synthetic RNA were mixed with the patients' blood cells, interferon levels (and thus, presumably, TLR3 activity) were normal.

This implies that the brain cells themselves must be able to produce TLR3 and interferons in order fight off infection, without help from the wider immune system.

"This is evidence of an intrinsic immunity, a newly-discovered function of the immune system," Zhang said. "It's likely that other organs also have their own specific tools for fighting infection."

The researchers are now planning a study to examine whether brain cells also exhibit signs of intrinsic immunity to types of viruses other than herpes. They are also planning a pilot study to see if Herpes simplex encephalitis can be treated directly using interferons, thereby bypassing the faulty TLR3 gene.

Sources:

http://www.sciencedaily.com/releases/2012/12/121210221259.htm