Featured Research

from universities, journals, and other organizations

Allergy-Producing Cells Are Also "Do-Gooders," Helping Stave Off Infections

Date:
July 7, 1999
Source:
Duke University
Summary:
Researchers at Duke University Medical Center have discovered that mast cells -- the same cells responsible for the miseries of allergy - also recognize harmful bacteria such as Salmonella and dangerous strains of E. coli and alert the immune system to destroy the bacteria.

DURHAM, N.C. - Researchers at Duke University Medical Center have discovered that mast cells -- the same cells responsible for the miseries of allergy - also recognize harmful bacteria such as Salmonella and dangerous strains of E. coli and alert the immune system to destroy the bacteria.

The researchers say the discovery, which appears in the July 6 issue of the Proceedings of the National Academy of Science, may lead to new ways to fight infections, particularly in patients whose immune systems are compromised during an organ transplant or HIV infection.

The research is supported by grants from the National Institutes of Health and the Medical Research Council.

"For years people have wondered why we have mast cells when they seem to do nothing but cause misery for people with allergy and asthma," said microbiologist Soman Abraham, lead investigator of the study. "Now we've shown that the mast cell has a crucial role in identifying potentially dangerous bacteria and alerting the immune system to destroy them."

The much maligned mast cells lie just beneath the surface of virtually all body tissues that have contact with the outside world: the skin, gut, nasal passages, lung and urinary tract. For years mast cells seemed only to be a sort of cry-wolf cell that overreact to the inhalation of substances as benign as pollen grains and release a flood of inflammatory molecules and histamine - the bane of allergy sufferers.

But Abraham and his colleagues discovered a more subtle but powerful role for mast cells. The researchers found a molecule called CD48 on the mast cell surface. CD48 recognizes a protein called FimH on the tips of hair-like projections on many infectious bacteria. This CD48-FimH connection triggers mast cells to alert the immune system by releasing a substance called tumor necrosis factor alpha (TNF-a), which is a type of early warning system of infection, Abraham said.

"We are bombarded with bacteria every day," Abraham said. "In healthy people, mast cells seem to help clear the body of bacteria quickly, so that you don't even know you've been infected. Only when you get such a huge dose of bacteria that the mast cells can't cope or when your immune system is compromised do the bacteria gain a foothold."

Typically, mast cells are not activated by the beneficial bacteria that inhabit the gut, because such bacteria colonize the surface of the intestinal lining, he said. Only when bacteria become invasive, burrowing into the gut lining, are the mast cells alerted.

The Duke scientists' discovery also appears to clear up a mystery about the function of the CD48 protein. Although CD48 was discovered more than 10 years ago as a protein that appears on the surface of some white blood cells such as mast cells, its biological role has not been clearly defined.

In their experiments, Abraham and his colleagues showed that antibodies to CD48 blocked mast cells from recognizing bacteria and stopped the mast cells from releasing the signaling molecule TNF-a in the presence of bacteria. This finding led the researchers to conclude that CD48 is a specific receptor on mast cells that recognizes bacteria and triggers the release of TNF-a, which alerts the immune system to destroy the bacteria.

The researchers will now try to find ways to beef up the mast cells' ability to fight bacteria in people with weakened immune systems, such as people infected by HIV or who are taking anti-rejection drugs following organ transplantation. Such a strategy might be a way to avoid overuse of traditional antibiotic treatment, said Abraham.

"Now that we know that CD48 is the important trigger, we can target treatments that would trip that trigger to help boost the immune system's ability to fight infection in people with immune deficiency," he added.

Ravi Malaviya, Zhimin Gao, Krishnan Thankavel and P. Anton van der Merwe also contributed to the research.


Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Cite This Page:

Duke University. "Allergy-Producing Cells Are Also "Do-Gooders," Helping Stave Off Infections." ScienceDaily. ScienceDaily, 7 July 1999. <www.sciencedaily.com/releases/1999/07/990707073205.htm>.
Duke University. (1999, July 7). Allergy-Producing Cells Are Also "Do-Gooders," Helping Stave Off Infections. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/1999/07/990707073205.htm
Duke University. "Allergy-Producing Cells Are Also "Do-Gooders," Helping Stave Off Infections." ScienceDaily. www.sciencedaily.com/releases/1999/07/990707073205.htm (accessed September 20, 2014).

Share This



More Health & Medicine News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com
How The 'Angelina Jolie Effect' Increased Cancer Screenings

How The 'Angelina Jolie Effect' Increased Cancer Screenings

Newsy (Sep. 19, 2014) Angelina's Jolie's decision to undergo a preventative mastectomy in 2013 inspired many women to seek early screenings for the disease. Video provided by Newsy
Powered by NewsLook.com
The Cost of Ebola

The Cost of Ebola

Reuters - Business Video Online (Sep. 18, 2014) As Sierra Leone prepares for a three-day "lockdown" in its latest bid to stem the spread of Ebola, Ciara Lee looks at the financial implications of fighting the largest ever outbreak of the disease. Video provided by Reuters
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:
from the past week

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