Finding suggests novel ways to boost vaccination or natural defenses

Jul 07, 2008

Our bodies rely on the production of potent, or 'high affinity', antibodies to fight infection. The process is very complex, yet Sydney scientists have discovered that it hinges on a single molecule, a growth factor, without which it cannot function.

There is much we do not yet understand about our immune system. In simple terms, our bodies produce B cells, which make antibodies, and T cells, which help them. Ways in which these cells operate and interact with each other are still coming to light.

Roughly eight years ago, a new subset of T cells, T follicular helper (TFH) cells, was identified. This important class of T cells operates in specific environments termed 'germinal centres', specialised areas within lymph organs where B cells proliferate to form high affinity antibodies whenever we fight infection. TFH cells play a critical role in that they communicate with, and help activate, B cells.

The novel finding made by Dr Cecile King and PhD student Alexis Vogelzang, from the Garvan Institute of Medical Research in Sydney, was that the molecule interleukin 21 (IL-21) is a growth factor for TFH cells. A paper detailing this finding was published online today in the prestigious international journal Immunity.

A cytokine, or chemical messenger, IL-21 is already well known to immunologists. While its newly identified growth factor role is only one of several functions, that function is fundamental. Without IL-21, the all-important TFH cells could neither develop nor survive.

Dr Cecile King, head of the Mucosal Autoimmunity Group at Garvan, has been investigating the roles of IL-21 for several years. "We already knew that IL-21 was produced by TFH cells and that it was a major initiator of proliferation in B cells," she said. "We were surprised to find that TFH cells not only produce IL-21, they also absolutely need it to survive and they utilise it to function."

"We showed that if you take a mouse genetically deficient in IL-21 and immunise it, you don't get TFH cells and you don't get antibody production. Conversely, if you put IL-21 receptor sufficient, or normal, T cells into the same mouse, where of course the B cells remain abnormal, you recover the normal immune reaction."

"These specialised T cells are thought to be the ones that direct traffic. They are the only ones that can move into the B cell zone and initiate high affinity antibody production."

"Without IL-21, we probably wouldn't be completely immunodeficient, just severely compromised. In addition to the high affinity antibodies we're talking about, our bodies also produce a lot of low affinity antibodies for mopping up infection. That low level response happens around-the-clock and is one of our body's first lines of defence."

"You could say that IL-21 directs the most finely-tuned aspect of our immune response. The highly specialised weaponry developed on-the-spot to target aggressive invaders."

"This finding suggests novel ways to boost vaccination or natural defences."

Source: Research Australia

Explore further: Molecule enhances copper's lethal punch against microbes

add to favorites email to friend print save as pdf

Related Stories

Fermi satellite detects gamma-rays from exploding novae

44 minutes ago

The Universe is home to a variety of exotic objects and beautiful phenomena, some of which can generate almost inconceivable amounts of energy. ASU Regents' Professor Sumner Starrfield is part of a team that ...

NASA sees Genevieve squeezed between 3 tropical systems

49 minutes ago

The resurrected Tropical Depression Genevieve appears squeezed between three other developing areas of low pressure. Satellite data from NOAA and NASA continue to show a lot of tropical activity in the Eastern ...

US warns retailers on data-stealing malware

54 minutes ago

US government cybersecurity watchdogs warned retailers Thursday about malware being circulated that allows hackers to get into computer networks and steal customer data.

Recommended for you

Small RNAs in blood may reveal heart injury

1 hour ago

(Medical Xpress)—Like clues to a crime, specific molecules in the body can hint at exposure to toxins, infectious agents or even trauma, and so help doctors determine whether and how to treat a patient. ...

Researchers uncover clues to flu's mechanisms

5 hours ago

A flu virus acts like a Trojan horse as it attacks and infects host cells. Scientists at Rice University and Baylor College of Medicine have acquired a clearer view of the well-hidden mechanism involved.

User comments : 0