Featured Research

from universities, journals, and other organizations

Too much of a good thing? Overactive immune response blocks itself

Date:
July 26, 2013
Source:
Helmholtz Centre for Infection Research
Summary:
As part of the innate immune system natural killer cells play an important role in immune responses. For a long time they have been known as the first line of defense in the fight against infectious diseases. Therefore, researchers assumed that the body needs as many active NK cells as possible. However, scientists have now shown that the principle "the more the better" does not apply to this type of immune cells.

When infected with Listeria monocytogenes (green) it is important to have the right immune cells present at the right time. Too many natural killer cells for example can block the recruitment of neutrophilic granulocytes (red) which are vital for the immune response.
Credit: © HZI / Jablonska

As part of the innate immune system natural killer cells (NK cells) play an important role in immune responses. For a long time they have been known as the first line of defense in the fight against infectious diseases. Therefore, researchers assumed that the body needs as many active NK cells as possible. However, scientists at the Helmholtz Centre for Infection Research (HZI) have now shown that the principle "the more the better" does not apply to this type of immune cells.

"During certain phases of the immune response it seems to be beneficial to have less active natural killer cells," says Dr Jadwiga Jablonska-Koch, member of the research group "Molecular Immunology" at the HZI and responsible author of a new study published in the European Journal of Immunology. "This is particularly true during the beginning stages of an infection, which is precisely when they were assumed to be most important."

Usually, Listeria monocytogenes infection leads to a deadly sepsis in mice and immune suppressed humans. Interestingly, researchers observed that removal of NK cells during the early stages of Listeria monocytogenes infection improves survival of the mice. These new findings could help to prevent sepsis in the future.

Until now it was believed that mice and humans die from listeriosis because their killer cells do not fight the infection effectively enough. However, the new results show the exact opposite. Even though the killer cells produce messenger substances that activate the immune system, the overproduction of the interferon IFN-γ causes problems. The large amounts of IFN-γ block the recruitment of neutrophilic granulocytes.

Those so-called scavenger cells are the most common white blood cells and are able to engulf bacteria and destroy them. If their migration to the site of infection is blocked in the initial phase, the bacteria can grow uncontrolled. This leads to fatal sepsis and death.

However, having no active NK cells could also lead to uninhibited bacteria proliferation. In later stages of an infection NK cells are crucial for the survival of both; mice and humans. "It is important to find the right balance for NK cell activity. It has to be high enough to activate other immune cells, but at the same time the migration and activation of scavenger cells shouldn't be blocked," says Jablonska-Koch.

Where exactly this balance lies is still not clear. At least, the scientists were able to show that in the later phases of infectious diseases it can be beneficial for the body to have large amounts of highly active NK cells. The discovery of HZI scientists could be relevant in the future, especially from a medical point of view. If these results prove to be true for humans and also for other bacteria, they could help to develop new treatment strategies. "If we know how exactly the killer cells function, we could use this information for treatment of bacterial infections. But it is still a long way to go," says Jablonska-Koch.


Story Source:

The above story is based on materials provided by Helmholtz Centre for Infection Research. Note: Materials may be edited for content and length.


Journal Reference:

  1. Nuno Viegas, Lisa Andzinski, Ching-Fang Wu, Ronja-Melinda Komoll, Nelson Gekara, Kurt E. Dittmar, Siegfried Weiss, Jadwiga Jablonska. IFN-γ production by CD27 NK cells exacerbatesListeria monocytogenesinfection in mice by inhibiting granulocyte mobilization. European Journal of Immunology, 2013; DOI: 10.1002/eji.201242937

Cite This Page:

Helmholtz Centre for Infection Research. "Too much of a good thing? Overactive immune response blocks itself." ScienceDaily. ScienceDaily, 26 July 2013. <www.sciencedaily.com/releases/2013/07/130726103355.htm>.
Helmholtz Centre for Infection Research. (2013, July 26). Too much of a good thing? Overactive immune response blocks itself. ScienceDaily. Retrieved September 23, 2014 from www.sciencedaily.com/releases/2013/07/130726103355.htm
Helmholtz Centre for Infection Research. "Too much of a good thing? Overactive immune response blocks itself." ScienceDaily. www.sciencedaily.com/releases/2013/07/130726103355.htm (accessed September 23, 2014).

Share This



More Health & Medicine News

Tuesday, September 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola Costs Keep Mounting

Ebola Costs Keep Mounting

Reuters - Business Video Online (Sep. 23, 2014) — The WHO has warned up to 20,000 people could be infected with Ebola over the next few weeks. As Sonia Legg reports, the implications for the West African countries suffering from the disease are huge. Video provided by Reuters
Powered by NewsLook.com
Ebola Cases Could Reach 1.4 Million Within 4 Months

Ebola Cases Could Reach 1.4 Million Within 4 Months

Newsy (Sep. 23, 2014) — Health officials warn that without further intervention, the number of Ebola cases in Liberia and Sierra Leone could reach 1.4 million by January. Video provided by Newsy
Powered by NewsLook.com
WHO: Ebola Cases to Triple in Weeks Without Drastic Action

WHO: Ebola Cases to Triple in Weeks Without Drastic Action

AFP (Sep. 23, 2014) — The number of Ebola infections will triple to 20,000 by November, soaring by thousands every week if efforts to stop the outbreak are not stepped up radically, the WHO warned in a study on Tuesday. Duration: 01:01 Video provided by AFP
Powered by NewsLook.com
5 Ways Men Can Prevent Most Heart Attacks

5 Ways Men Can Prevent Most Heart Attacks

Newsy (Sep. 23, 2014) — No surprise here: A recent study says men can reduce their risk of heart attack by maintaining a healthy lifestyle, which includes daily exercise. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins