Featured Research

from universities, journals, and other organizations

Scans Show Immune Cells Intercepting Parasites

Date:
December 20, 2008
Source:
Washington University School of Medicine
Summary:
Researchers may have identified one of the body's earliest responses to a group of parasites that causes illness in developing nations and are now infecting US soldiers on patrol in Iraq and Afghanistan.

Researchers may have identified one of the body's earliest responses to a group of parasites that causes illness in developing nations.

In a paper published online in Public Library of Science Pathogens, scientists report that they tracked immune cells as they patrolled the second-shallowest layer of the skin in an animal model. Injections of a genetically modified form of the parasite Leishmania major caused the immune cells to turn from their patrols and move to intercept the parasites.

The same parasites are now infecting U.S. soldiers on patrol in Iraq and Afghanistan, where sand flies, the insects whose bites spread Leishmania, are endemic. The infections normally do not cause symptoms, but the parasite can reactivate and cause complications during pregnancy or if the immune system weakens, including skin sores, fever, damage to the spleen and liver and anemia.

"This is one of our most detailed looks so far at how a first responder in the immune system scouts out pathogens," says co-author Stephen Beverley, Ph.D., the Marvin A. Brennecke Professor and head of the Department of Molecular Microbiology at Washington University School of Medicine in St. Louis. "Determining how the immune system reacts is critically important for efforts to develop vaccines that protect against these parasites."

According to Beverley, what researchers learn from Leishmania also may have applications for controlling more harmful parasites from the same family of microbes, the trypanosomes. These include Trypanosomiasis, the cause of African sleeping sickness, which disrupts the lymph, circulatory and nervous systems and is fatal if untreated, and Chagas disease, which can damage the heart and the intestine in long-term infections.

The study began with an attempt to better understand the role of a group of immune cells known as dendritic cells in the dermis, the second layer of the skin. Scientists at the University of Pennsylvania created a line of mice genetically modified so their dendritic cells produced a yellow fluorescent protein. They used a technique called two-photon microscopy to track the movements of the cells in living mice and show that the cells were "surprisingly motile around the perimeter, moving about and doing all sorts of patrolling," according to Beverley.

One of Beverley's graduate students, Michael A. Mandell, took a strain of Leishmania genetically modified to produce red fluorescent protein and injected it into the Pennsylvania group's mice. The different colors allowed them to use two-photon microscopy to track both dendritic cells and parasites at the same time, and they found that the dendritic cells rapidly homed in on the injected parasites.

Dendritic cells are antigen-presenting cells, which means they can absorb invaders and then display bits of them on their surface to other immune system cells. This triggers a heightened counterattack against the invaders from a variety of immune cells.

Injections of latex beads did not cause the same response from the dendritic cells.

"The dendritic cells were clearly recognizing something made by the pathogen that was provoking their response, and that's one question we will be looking to answer in follow-up experiments," Beverley says.

Beverley notes that infection with Leishmania and other parasites can cause different diseases in different people, suggesting that genetic differences in parasite and host can alter the immune response. Methods of transmission in the wild are messier than an injection and may also add variety to those responses.

"Many of the insects that pass on these parasites are not elegant eaters—they chew on skin, creating pools of many cell types," he explains. "The big question is: How do all the different immune cell types combine to orchestrate the immune system's response? What we've done is to pull out one leading player from that mix, which is an important first step to understanding the overall response."

Funding from the National Institutes of Health, the National Health and Medical Research Council, the New South Wales Life Sciences Award and the Cancer Research Institute supported this research.


Story Source:

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


Journal Reference:

  1. Ng et al. Migratory Dermal Dendritic Cells Act as Rapid Sensors of Protozoan Parasites. PLoS Pathogens, 2008; 4 (11): e1000222 DOI: 10.1371/journal.ppat.1000222

Cite This Page:

Washington University School of Medicine. "Scans Show Immune Cells Intercepting Parasites." ScienceDaily. ScienceDaily, 20 December 2008. <www.sciencedaily.com/releases/2008/12/081210171904.htm>.
Washington University School of Medicine. (2008, December 20). Scans Show Immune Cells Intercepting Parasites. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2008/12/081210171904.htm
Washington University School of Medicine. "Scans Show Immune Cells Intercepting Parasites." ScienceDaily. www.sciencedaily.com/releases/2008/12/081210171904.htm (accessed April 20, 2014).

Share This



More Health & Medicine News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nine-Month-Old Baby Can't Open His Mouth

Nine-Month-Old Baby Can't Open His Mouth

Newsy (Apr. 19, 2014) Nine-month-old Wyatt Scott was born with a rare disorder called congenital trismus, which prevents him from opening his mouth. Video provided by Newsy
Powered by NewsLook.com
'Holy Grail' Of Weight Loss? New Find Could Be It

'Holy Grail' Of Weight Loss? New Find Could Be It

Newsy (Apr. 18, 2014) In a potential breakthrough for future obesity treatments, scientists have used MRI scans to pinpoint brown fat in a living adult for the first time. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. Video provided by Newsy
Powered by NewsLook.com
Scientists Create Stem Cells From Adult Skin Cells

Scientists Create Stem Cells From Adult Skin Cells

Newsy (Apr. 17, 2014) The breakthrough could mean a cure for some serious diseases and even the possibility of human cloning, but it's all still a way off. 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:
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