We may be wonder, why our immune system is able to fight off some viruses and why not on HIV or Hepatitis C? A new University of California (UCLA) AIDS Institute study has found the answer for this situation! They found that a protein called interlukin-21(IL-21) which released by our immune system during infection is the answer.
To lead them to this finding, the researchers looked at two types of immune cells which are CD4 T and CD8 T. In response to infection to chronic infection, CD4 T produces IL-21, bolstering CD8-T ability to fight off the viruses. To determine how CD4 T-cells help their CD8 counterparts clear viruses, the researchers using mice test. They infected mice with two strains of a virus. They knew that the first strain would generate a short-term infection and the second a chronic infection
The scientists tested each strain on two groups of mice. One group was normal and the other was bred without IL-21 receptors.
In the normal mice, the first strain brought out a strong T-cell response that completely eliminated the virus in 10 days. The second strain caused a chronic infection that exhausted the T-cells, slowing down their ability to fight the virus. The UCLA team detected high levels of IL-21 in these mice, suggesting that the protein plays a crucial role in sustaining the T-cells' ability to increase an immune response during long-lasting infection.
When the scientists infected the mice that lacked IL-21 receptors with the chronic infection strain, something curious happened. The majority of virus-fighting CD8 T-cells disappeared, preventing the immune system from controlling the spread of the virus. This shows that CD8 T cells is depend on IL-21 to be functioning.
REFERENCE:
University of California - Los Angeles (2009, May 7). Key Protein Keeps Chronic Infection In Check. ScienceDaily. Retrieved May 10, 2009, from
http://www.sciencedaily.com /releases/2009/05/090508103842.htm
To lead them to this finding, the researchers looked at two types of immune cells which are CD4 T and CD8 T. In response to infection to chronic infection, CD4 T produces IL-21, bolstering CD8-T ability to fight off the viruses. To determine how CD4 T-cells help their CD8 counterparts clear viruses, the researchers using mice test. They infected mice with two strains of a virus. They knew that the first strain would generate a short-term infection and the second a chronic infection
The scientists tested each strain on two groups of mice. One group was normal and the other was bred without IL-21 receptors.
In the normal mice, the first strain brought out a strong T-cell response that completely eliminated the virus in 10 days. The second strain caused a chronic infection that exhausted the T-cells, slowing down their ability to fight the virus. The UCLA team detected high levels of IL-21 in these mice, suggesting that the protein plays a crucial role in sustaining the T-cells' ability to increase an immune response during long-lasting infection.
When the scientists infected the mice that lacked IL-21 receptors with the chronic infection strain, something curious happened. The majority of virus-fighting CD8 T-cells disappeared, preventing the immune system from controlling the spread of the virus. This shows that CD8 T cells is depend on IL-21 to be functioning.
REFERENCE:
University of California - Los Angeles (2009, May 7). Key Protein Keeps Chronic Infection In Check. ScienceDaily. Retrieved May 10, 2009, from
http://www.sciencedaily.com /releases/2009/05/090508103842.htm
