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Immune System

An immune system is a collection of mechanisms within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function properly. Detection is complicated as pathogens adapt and evolve new ways to successfully infect the host organism.
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March 7th, 2010

Immune Disturbances Genetically Linked to Celiac Disease

New genetic links may help doctors in the early detection of celiac disease, or celiac sprue, which is an autoimmune disease that causes the body to become intolerant of gluten.

Photo by: Emiline220, Flikr, Creative CommonsProfessor David van Heel of Barts and The London School of Medicine and Dentistry led a team of international professionals that examined genetic material from 9,451 people with celiac disease. Researchers found that people with celiac disease had disturbances in how the body’s T cells react to wheat proteins, how the thymus gland eliminates these cells, and how the body responds to viral infections.

“We now understand that many of these genetic risk factors work by altering the amounts of these immune system genes that cells make,” van Heel explained in a press release. “The data also suggests that celiac disease is made up of hundreds of genetic risk factors. We can have a good guess at nearly half of the genetic risk at present.”

Gluten is found in products made from wheat, barley, and rye. When a person with celiac eats foods that contain gluten, the villi in the small intestine are damaged or destroyed and cannot absorb nutrients. Symptoms include stomach pain, vomiting or nausea, diarrhea, and unexplained weight loss.

The only way to treat celiac disease is to adopt a gluten-free diet. If left unmanaged, it can cause malnutrition, fatigue, osteoporosis, and anemia. Understanding these risks could help doctors predict and detect celiac disease before these complications arise.

This research could provide insight into other autoimmune diseases. According to van Heel, there may be reason to believe the same immune disturbances used to detect celiac disease could also potentially be used to predict type 1 diabetes.

The study appears in the February 28 edition of Nature Genetics.

March 6th, 2010

Building Tolerance a Possible Solution to Peanut Allergy

Baby steps may be the key to helping people with peanut allergies. Gradually increasing exposure may help them build up a tolerance that could prevent bad reactions to accidental ingestion in the future.

Photo by: jrsnchzhrs, Flikr, Creative CommonsMost people who are allergic to peanuts are also allergic to tree nuts. Someone with a less sensitive allergy may be able to tolerate certain co-products, such as peanut oil, but most aren’t so lucky. Even trace amounts of peanut products can set off a reaction.

"At the start of the study, these participants couldn't tolerate one-sixth of a peanut," Dr. Wesley Burks, chief of Duke’s Pediatric Allergy and Immunology division, said in a press release following the first trial. "Six months into it, they were ingesting 13 to 15 peanuts before they had a reaction."

Co-author Dr. Tamara Perry, of the University of Arkansas for Medical Sciences, explained to Health Day that this research is not meant to help people eat peanuts, but to help prevent the severe reactions that come with accidental ingestion.

A peanut allergy can cause skin reactions (such as hives or swelling), diarrhea, and nausea/vomiting. It can also cause lightheadedness, a stuffy nose, or itchy, watery eyes. In more extreme reactions, blood pressure may drop to dangerous levels and cause difficulty breathing, sometimes resulting in loss of consciousness.

Researchers from Duke University ran several tests investigating the effectiveness of immunotherapy treatment. Fifteen children ate small amounts of food with peanut ingredients in slowly increasing amounts every day.

Although there were several reactions over the course of the study, children could safely consume 5,000 milligrams (about 15 peanuts) by the experiment’s finish. Eight of these children were re-tested after four weeks away from the program, and all were able to eat peanuts safely.

"Of course the ultimate goal would be to promote tolerance that would allow these patients—children and adults—to eat peanuts,” Perry told Health Day. “The immunotherapy work being carried out now shows a lot potential promise in that direction."

The success of Duke’s peanut immunotherapy treatment is hopeful, but more testing is needed to determine whether some of the effects were a result of children growing out of the allergy. Research is still in the early stages and should not be tried at home.

Read more about Duke’s research in the Duke University article.

November 20th, 2009

You Can Actually Get Two Colds At Once

Batten down the hatches and break out the vitamin C. Cold season is officially here, and it’s possible to get two strains at once!

Photo by: EyeSoGreen, Flikr, Creative CommonsTwo new studies of human rhinovirus (HRV), the common cold, have welcomed a new cold bug to the family. Previously, there were only two known species of the virus—HRV-A and HRV-B. Now a third, HRV-C, can be added to the list.

The HRV-A and HRV-B species alone represent different strains of the virus, 99 to be exact. What’s surprising is that HRV-C, which has an additional seven strains, appears to be a hybrid of both.

Researchers of the first study discovered the new species while doing genome sequences for all 99 strains of the original HRV set. Genome sequencing allows scientists to break down and more closely examine a virus’ RNA to find different combinations of genetic material.

When a person carries two strains of a virus, the strains can come together to exchange this material, a process called recombination. Because the new species shares characteristics of both HRV-A and HRV-B, researchers have concluded that it is possible for a person to carry both strains at once. So yes, you can have two colds at once.

“Coinfection with multiple HRVs is known to occur,” authors of the second study write, “We now know that this can lead to strains that may have distinct biologic properties and clinical characteristics.”

The second study examined 64 Chinese children, many of whom had what they called a “triple infection.” Many had a form of rhinovirus and another respiratory virus (such as the flu), but some had two rhinovirus strains in addition to another respiratory virus.

When the body hosts a cocktail of viruses, this makes it easier for different strains to exchange RNA and multiply quickly. Further investigation suggests that there may actually be another species of the cold on the way—HRV-D.

Researchers of the second study plan to continue exploring HRV genetic material, and hope this will help lead to better treatment and more effective medications.

“The clustering of small clades (biological groups), the recombinations, and the mutations found in all regions of these genomes suggest that future HRV epidemiologic studies might benefit from full genome sequencing rather than the more limited serotyping,” they say.

October 26th, 2009

Acetaminophen After Boosters May Weaken Infant Immune Systems

Parents often give their infants acetaminophen (Tylenol) after immunizations and booster shots. As it turns out, this may do more harm than good. The medication may actually weaken infants’ immune systems, according to research from the Czech Republic.

Photo by: Andres Ruedas, Creative Commons, FlikrAcetaminophen is sometimes given to infants and small children following shots to prevent fever, a common reaction to vaccinations. This study examined the effects of acetaminophen on immune response after initial and booster vaccinations.

Two hundred twenty-six children from 10 different medical centers were randomly selected to receive three doses every six to eight hours for 24 hours after immunizations. Just 42 percent of these children experienced fevers (100.4 degrees F or above), compared to 66 percent of a control group of 233.

When it was time for booster shots, parents were asked to repeat the process. There was a lower incidence of fever in both groups—36 percent for those who took acetaminophen and 58 percent for those who did not.

Children who received acetaminophen , however, had fewer antibodies, indicating more susceptibility to disease. In the studied children, pneumonia, hepatitis B, whooping cough, polio, diphtheria and tetanus antibodies were fewer following vaccinations and boosters with acetaminophen use.

Antibodies are proteins in the immune system (immunoglobulins) that bind to harmful pathogens (viruses) to keep them away from healthy white blood cells. Without these antibodies, the body’s immune system is more susceptible to disease.

When vaccines fail to protect against diseases, the health of the entire community is at stake because viruses are more easily spread.

“This point has implications, especially for Haemophilus influenzae, for which higher and sustained antibody concentrations are needed (to reduce transmission),” says Dr. Robert T Chen of the Centers for Disease Control in Atlanta, “…and for pertussis, the bacterial vaccine-preventable disease that is least controlled.”

Although they’re not entirely sure why children taking acetaminophen had fewer antibodies, doctors plan to explore the issue further. They stress the importance of this information, and advise against unnecessary acetaminophen use.

“(A)dministration of antipyretic drugs at the time of vaccination should nevertheless no longer be routinely recommended without careful weighing of the expected benefits and risks,” wrote lead author Dr. Roman Pryula of the University of Defense in Hradec Kralove, Czech Republic.

The study appears in this month’s online issue of The Lancet.

September 21st, 2009

Showerheads Home to Bacteria

Your showerhead may be home to some very dangerous bacteria. A new study from the University of Colorado at Boulder may have you cringing rather than singing in the shower. People with compromised immune systems may want to take a bath.

Photo by: stevendepolo, Flickr, Creative CommonsResearchers studying the microbiology of water systems at 45 sites in seven different states across the U.S. found unusually high levels of bacteria in showerheads—almost 100 times more than any other place in the home. Although bacteria levels were high in all showerheads, some sample sites in the New York City and Denver areas had large amounts of Mycobacterium avium, a relative of the bacteria that causes tuberculosis and leprosy.

“If you’re getting a face full of water when you first turn your shower on, that means you are probably getting a particularly high load of Mycobacterium avium,” says study author Norman Pace, professor of biology at the University of Colorado.

Mycobacteria are found in soil, water, and decaying matter. Certain Mycobacteria, such as Mycobactrium avium, can cause digestive, lymphatic, and pulmonary infections. In the shower, these bacteria are delivered as aerosols. Particles are small enough to get into the lungs, and when inhaled or swallowed, can lead to a host of pulmonary problems.

The study, part of a bigger study that began as a class project, used DNA barcode testing to extract rRNA (bacterial DNA) from different parts of the shower and showerhead. Researchers sampled water flowing from the showerhead and obtained swab samples from the inside of the showerhead. Finally, samples were collected from water flowing out of the pipe after the showerhead was removed.

Homes with well water systems did not have Mycobacteria in their showerheads, a factor authors believe may be due to Mycobacteria’s chlorine resistance. Although they suggest that bathing may be safer, researchers assure that it’s not dangerous to shower.

“We did see some organisms that might be of concern if you have immune issues (such as) cystic fibrosis, AIDS, recent organ transplant, substance abuse, or are pregnant or otherwise immune compromised,” the authors wrote.

Click for more information on pulmonary disease.

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