What is the function of lymph nodes?

May 26, 2009

If we imagine our immune system to be a police force for our bodies, then previous work has suggested that the Lymph nodes would be the best candidate structures within the body to act as police stations - the regions in which the immune response is organised.

However, Prof. Burkhard Becher, University of Zurich, suggests in a new paper - published in this week's issue of - that are not essential in the mouse in marshalling T-cells (a main immune foot soldier) to respond to a breach of the skin barrier. This result is both surprising in itself, and suggests a novel function for the liver as an alternate site for T-cell activation.

When a child falls off its bike and scratches its skin, the body responds via the immune system. Scavenger cells at the site of the wound pick up antigens -tiny particles derived from invading microorganisms and dirt that the body will recognize as foreign. These antigens are delivered to the nearest lymph node. T and () carrying the matching antigen-receptors on their surface will be stimulated by the concentrated antigen now present in these lymph nodes. T cells will then go on and orchestrate the defensive response against the invaders, whereas B cells will transform into antibody-producing cells flooding the body with antibodies which act against the hostile microorganisms.

Mice that lack lymph nodes due to a genetic mutation (alymphoplasia) are severely immuno-compromised and struggle in fighting infections and tumors. New work by Melanie Greter, Janin Hofmann and Burkhard Becher from the Institute of experimental Immunology at the University of Zurich reports that the immunodeficiency associated with alymphoplasia is not due to the lack of lymph nodes, but caused by the genetic lesion on immune cells themselves. The new paper shows that in the mouse T cell function is unperturbed in the absence of lymph nodes, whereas B cell activation and antibody secretion is strongly affected. That T cell responses can be launched outside of lymph nodes is highly surprising, because this means that T cells can encounter antigens elsewhere in order to become activated.

By tracing the migration of fluorescent particles from the site of antigen invasion (i.e. the wound) the scientists discovered that the liver could serve as a surrogate structure for T cell activation. During embryonic development, the liver is the first organ to provide us with blood and immune cells. Apparently, at least in the mouse the liver continues to serve as an "immune organ" even during adulthood.

This work suggests an explanation for the curious fact that patients receiving a liver transplant sometimes inherit the donor's allergies and immune repertoire, so in keeping with the idea that donor immune information is being transplanted. It also suggests that the liver as an immune organ is an evolutionary remnant from the time before lymph nodes developed in higher birds and mammals.

Cold-blooded vertebrates have functioning T and B cells but no lymph nodes. The main achievement of the development of lymph nodes in mammals is a drastic improvement for the production of better antibodies. on the other hand have not changed their function much during evolution and the work by the Zurich group finally provides solid evidence for the versatility and promiscuity of this cell type.

Source: University of Zurich

Explore further: Researchers successfully clone adult human stem cells

add to favorites email to friend print save as pdf

Related Stories

New origin found for a critical immune response

Mar 01, 2009

An immune system response that is critical to the first stages of fighting off viruses and harmful bacteria comes from an entirely different direction than most scientists had thought, according to a finding by researchers ...

Immune cells reveal fancy footwork

Dec 01, 2008

Our immune system plays an essential role in protecting us from diseases, but how does it do this exactly? Dutch biologist Suzanne van Helden discovered that before dendritic cells move to the lymph nodes they lose their ...

Recommended for you

Researchers successfully clone adult human stem cells

Apr 18, 2014

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Researchers develop new model of cellular movement

Apr 18, 2014

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

For resetting circadian rhythms, neural cooperation is key

Apr 17, 2014

Fruit flies are pretty predictable when it comes to scheduling their days, with peaks of activity at dawn and dusk and rest times in between. Now, researchers reporting in the Cell Press journal Cell Reports on April 17th h ...

User comments : 0

More news stories

Plants with dormant seeds give rise to more species

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.

Health care site flagged in Heartbleed review

People with accounts on the enrollment website for President Barack Obama's signature health care law are being told to change their passwords following an administration-wide review of the government's vulnerability to the ...