Featured Research

from universities, journals, and other organizations

Helper T cells, not killer T cells, might be responsible for clearing hepatitis A infection

Date:
July 16, 2012
Source:
Nationwide Children's Hospital
Summary:
Helper cells traditionally thought to only assist killer white blood cells may be the frontline warriors when battling hepatitis A infection.

Helper cells traditionally thought to only assist killer white blood cells may be the frontline warriors when battling hepatitis A infection. These are the findings from a Nationwide Children's Hospital study appearing in a recent issue of the Journal of Experimental Medicine.

Related Articles


Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus. Despite the availability of an effective vaccine, the virus infects millions of people worldwide each year and remains a global public health problem, especially in underdeveloped countries.

Unlike the hepatitis C virus, the hepatitis A virus does not establish a persistent infection. Yet, up to 20 percent of patients can relapse several weeks after virus growth and after symptoms have disappeared.

"Mechanisms of immunity that protect against relapse, and why they occasionally fail, are unknown," said the study's lead author Christopher M. Walker, PhD, director of the Center for Vaccines and Immunity at The Research Institute at Nationwide Children's Hospital.

Research has shown that white blood cells known as CD8+ killer T cells play a critical role in controlling hepatitis C and hepatitis B virus infections. These T cells act by killing infected liver cells, a process that damages the liver, but is necessary to effectively shut off production of new viruses.

A study published more than 20 years ago suggested that killer T cells also control hepatitis A virus infection in humans. However, Dr. Walker observed a very different pattern of immunity while studying acute hepatitis A virus infection in animals.

He found that the infection was controlled well before an effective killer T cell response was generated. Hepatitis A virus growth was instead controlled by CD4+ T helper cells, a different type of white blood cell that normally assists in the activation killer T cells but, is not thought to directly engage virus-infected cells. In the two infected animals infected with the hepatitis A virus, helper T cells secreted factors that suppressed virus growth without causing serious liver damage or inflammation that is an undesirable byproduct of a killer T cell response.

Moreover, the helper T cells responded to resurgence in hepatitis A virus growth after initial control of the infection, and remained strong until the virus was finally eliminated from the liver several months later. These findings suggested that CD8+ T cells are not necessarily required to control hepatitis A virus infection. Instead, it appears that CD4+ T cells have a more direct role in stopping replication of the hepatitis A virus by mechanisms that do not involve severe damage to the liver.

"This is quite an unusual discovery," said Dr. Walker, also a faculty member at The Ohio State University College of Medicine. "These findings document a previously unappreciated role for CD4+ T cells in resolving acute hepatitis A, and perhaps in surveillance against a relapse in virus growth and liver disease that sometimes occurs in those with weak immune systems, particularly the very young and old."

If CD4+ T cells are found to play a similar role in humans, they could serve as a new target for preventing relapse of hepatitis A virus infection. An inefficient helper T cell response might explain why some patients relapse after clearing the infection.

"If CD4+ T cells have an immune surveillance function, as suggested by our findings, patients at greatest risk of relapsing liver disease may benefit from a vaccine that would boost helper T cell activity until the virus is finally cleared from the liver," said Dr. Walker.


Story Source:

The above story is based on materials provided by Nationwide Children's Hospital. Note: Materials may be edited for content and length.


Journal Reference:

  1. Y. Zhou, B. Callendret, D. Xu, K. M. Brasky, Z. Feng, L. L. Hensley, J. Guedj, A. S. Perelson, S. M. Lemon, R. E. Lanford, C. M. Walker. Dominance of the CD4 T helper cell response during acute resolving hepatitis A virus infection. Journal of Experimental Medicine, 2012; DOI: 10.1084/jem.20111906

Cite This Page:

Nationwide Children's Hospital. "Helper T cells, not killer T cells, might be responsible for clearing hepatitis A infection." ScienceDaily. ScienceDaily, 16 July 2012. <www.sciencedaily.com/releases/2012/07/120716124354.htm>.
Nationwide Children's Hospital. (2012, July 16). Helper T cells, not killer T cells, might be responsible for clearing hepatitis A infection. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2012/07/120716124354.htm
Nationwide Children's Hospital. "Helper T cells, not killer T cells, might be responsible for clearing hepatitis A infection." ScienceDaily. www.sciencedaily.com/releases/2012/07/120716124354.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) — The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Daily Serving Of Yogurt Could Reduce Risk Of Type 2 Diabetes

Daily Serving Of Yogurt Could Reduce Risk Of Type 2 Diabetes

Newsy (Nov. 25, 2014) — Need another reason to eat yogurt every day? Researchers now say it could reduce a person's risk of developing type 2 diabetes. Video provided by Newsy
Powered by NewsLook.com
Madagascar Working to Contain Plague Outbreak

Madagascar Working to Contain Plague Outbreak

AFP (Nov. 24, 2014) — Madagascar said Monday it is trying to contain an outbreak of plague -- similar to the Black Death that swept Medieval Europe -- that has killed 40 people and is spreading to the capital Antananarivo. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
Are Female Bosses More Likely To Be Depressed?

Are Female Bosses More Likely To Be Depressed?

Newsy (Nov. 24, 2014) — A new study links greater authority with increased depressive symptoms among women in the workplace. 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