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Artificial proteins alter immune function
Issue date: 3/6/08
Hopkins scientists have development a technique that boosts the immune system, offering an intriguing new way to modify its activity. The group, led by Scheherezade Sadegh-Nasseri from the School of Medicine, created artificial proteins that could help researchers create a new type of vaccine.
The human immune system is designed to protect the body from foreign invasive particles, called pathogens, such as bacteria and viruses. The first step in this defense is to recognize the pathogens, which the immune system does using specialized cells called B-cells, among others.
B-cells will ingest or destroy a foreign body, like a bacterium, that is floating around in the bloodstream. B-cells then take a little piece of protein from the bacterium, an identifying mark called an antigen, and put it on their own surface.
Antigen presentation, as it is called, allows other immune cells, called T-cells, to recognize the offending bacteria and attack them. In this way, the immune system can target and destroy specific pathogens.
Sadegh-Nasseri and her team found a way to enhance the B-cell's recognition of pathogens, which causes an increase in immune activity. They did this by manipulating the major histocompatibility complex, or MHC.
The MHC is a protein on the surface of B-cells that acts a bit like a roadside billboard. The MHC captures antigens from bacteria or other pathogens and then holds them out for T-cells to see. Once a T-cell sees an antigen on a B-cell, it knows what kind of pathogen to attack.
If they could alter the function of the MHC, Sadegh-Nasseri and her team reasoned, it might be possible to manipulate the immune system to recognize artificial antigens.
The MHC, like all proteins, is made inside the cell. While it is being processed on its way to the cell surface, its groove - the place where an antigen will eventually bind - is held open by another protein called CLIP.
Once the MHC gets to the cell surface, it is ready to bind to an antigen. A protein called DM catalyzes the exchange of CLIP for an antigen inside the groove.
The Hopkins group engineered a few proteins, called helper peptides, which can replace the function of DM. By expressing these proteins in immune cells, they were able to improve the efficiency of antigen presentation on B-cells and actually increase the T-cell response.
This research has many implications for immune biology. One of the possibilities from this research is improved vaccination. By injecting helper peptides along with antigens, the effectiveness of a vaccine could be increased.
The human immune system is designed to protect the body from foreign invasive particles, called pathogens, such as bacteria and viruses. The first step in this defense is to recognize the pathogens, which the immune system does using specialized cells called B-cells, among others.
B-cells will ingest or destroy a foreign body, like a bacterium, that is floating around in the bloodstream. B-cells then take a little piece of protein from the bacterium, an identifying mark called an antigen, and put it on their own surface.
Antigen presentation, as it is called, allows other immune cells, called T-cells, to recognize the offending bacteria and attack them. In this way, the immune system can target and destroy specific pathogens.
Sadegh-Nasseri and her team found a way to enhance the B-cell's recognition of pathogens, which causes an increase in immune activity. They did this by manipulating the major histocompatibility complex, or MHC.
The MHC is a protein on the surface of B-cells that acts a bit like a roadside billboard. The MHC captures antigens from bacteria or other pathogens and then holds them out for T-cells to see. Once a T-cell sees an antigen on a B-cell, it knows what kind of pathogen to attack.
If they could alter the function of the MHC, Sadegh-Nasseri and her team reasoned, it might be possible to manipulate the immune system to recognize artificial antigens.
The MHC, like all proteins, is made inside the cell. While it is being processed on its way to the cell surface, its groove - the place where an antigen will eventually bind - is held open by another protein called CLIP.
Once the MHC gets to the cell surface, it is ready to bind to an antigen. A protein called DM catalyzes the exchange of CLIP for an antigen inside the groove.
The Hopkins group engineered a few proteins, called helper peptides, which can replace the function of DM. By expressing these proteins in immune cells, they were able to improve the efficiency of antigen presentation on B-cells and actually increase the T-cell response.
This research has many implications for immune biology. One of the possibilities from this research is improved vaccination. By injecting helper peptides along with antigens, the effectiveness of a vaccine could be increased.
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