Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Immune system police learn early and sometimes badly

07.08.2006
Regulatory T cells, which function like immune system police, learn early in life what to protect, and that may include viruses, bacteria and tumors, researchers have shown.

Using genetically manipulated mice and technology that enables a snapshot of the repertoire of antigen receptors that determine what cells recognize, Medical College of Georgia researchers followed T cells as they spent time in the thymus then moved to the body.

They found regulatory T cells learn what to protect while in the thymus and that everything the cells learn may not be good, according to research in the August issue of Immunity.

It is widely believed that regulatory T cells only recognize endogenous body tissue so they can stop T cells that are predisposed to attacking it, says Dr. Leszek Ignatowicz, MCG immunologist and the study’s corresponding author.

By examining receptors on all types of T cells before and after they leave the thymus, researchers found regulatory T cells are very diverse and able to recognize endogenous tissue and invaders, Dr. Ignatowicz says.

Unfortunately, the cells also may not learn to recognize all endogenous tissue which, along with environmental and other factors, can lead to autoimmune disease.

T cell schooling in the thymus peaks in the first six weeks of life in the mouse, which roughly translates to the first 15 years of human life. Those early lessons seem to last a lifetime and the few regulatory cells that develop later will be like the early cells, says Dr. Rafal Pacholczyk, MCG immunologist and lead author.

The findings mean, essentially from the beginning, some people may have regulatory T cells less skilled at keeping the immune system from attacking their bodies and/or too skilled at protecting invaders.

It also means one day physicians might steer early education of regulatory T cells in the thymus as a way to vaccinate children against diseases such as lupus, arthritis and type 1diabetes. Or, they might add regulatory T cells to improve the mix in people who already have some bad police.

“We need some of the regulatory cells more than others,” says Dr. Ignatowicz. “We probably need more of the ones that recognize autoantigens on the pancreas and we need the ones that recognize tumors to be less frequent.”

The fact that most regulatory T cells in the body come directly from the thymus, not from other circulating T cells, also was previously unknown, Dr. Pacholczyk says. “Where they come from is the main question we wanted to answer,” says Dr. Ignatowicz.

It has been thought that some T cells circulating in the body might make the transformation, possibly because of what they are exposed to in the body. In fact T cells most aggressive at attacking endogenous tissue likely would be among those converting to protective regulatory cells, Dr. Ignatowicz says. “We did not find that does not happen, but it’s not the major mechanism for generating regulatory cells in the body,” Dr. Pacholczyk says.

All T cells are made in the bone marrow then move to the thymus as progenitor cells where they differentiate, upregulating surface receptors, which are molecules that detect different antigens. It’s a brutal process – 95 percent of the cells die in the thymus primarily because they recognize body tissue – that winds down after puberty.

All T cells wear their receptors for life, like signature hats. “We decided to compare receptors on the regulatory cells in the periphery with those in the thymus,” says Dr. Pacholczyk. By analyzing receptors on individual cells, they were able to follow the cells after they left the thymus and see if they changed.

Another key question was how regulatory T cells, which make up about 5 percent of the total T cell population, can control millions of roaming T cells. They found it was a simple matter of numbers: by wearing many hats, or antigen receptors, regulatory T cells can keep their eyes on a lot of different non-regulatory cells.

“The next question we will ask, which is a hot topic right now, is what antigens trigger receptors on regulatory T cells?” says Dr. Pacholczyk. “What do they recognize? We know now they are coming from the thymus but how they are being generated is still a question. We want to look into the nature of antigens those receptors recognize which will allow us to predict more how they are being developed in the thymus.”

Other study authors include Dr. Hanna Ignatowicz, geneticist, and Dr. Piotr Kraj, immunologist.

The research was funded by the National Institutes of Health and the Roche Foundation.

Toni Baker | EurekAlert!
Further information:
http://www.mcg.edu

More articles from Life Sciences:

nachricht Closing in on advanced prostate cancer
13.12.2017 | Institute for Research in Biomedicine (IRB Barcelona)

nachricht Visualizing single molecules in whole cells with a new spin
13.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>