Although cells of the immune system have good memories for antigens, their appearance can sometimes confuse them. In this case, however, mistakes are working to our advantage – we read in New Scientist.
When a new bacterium or virus enters the body, the immune system starts an attack by sending out T cells that are adapted to the intruder’s molecular structure. The fight may go on for several weeks, but after a victory, T cells remember the enemy, so they are able to defeat him faster when he shows up again.
Mark Davis of Stanford University in California analyzed 26 blood samples that had never been infected with HIV, herpes simplex virus (HSV), or cytomegalovirus (CMV). Nevertheless, each of the samples contained T cells adapted to fight these viruses. Half of them were immune memory cells.
The widely held view is that cells that store knowledge about an antigen are formed only in response to contact with it. But it turns out that different antigens may be so similar in structure that they can confuse the cells of the immune system, says Davis.
To test their assumptions, the scientists vaccinated two people against the H1N1 flu virus, which made T cells respond also to two bacteria with a similar structure. An immune response to HIV was observed when blood samples were confronted with gut and soil bacteria, as well as a bacterium found in marine algae.
Scientists hope that by discovering new cases of cross-reactivity, it will be possible to produce more effective vaccines in the future. (PAP)
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