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Teaching an Old Immune System New Tricks

Researchers have found a protein that may be the immune system's fountain of youth.

Researchers from Germany's Hemholtz Centre for Infection Research may have discovered a treatment to make old immune systems young again. Their results, published in the Journal of Pathology, suggest that a growth protein may have a "fountain of youth" effect on the immune system.

The scientists, led by Eva Medina, examined the immune system decline associated with aging. By comparing immune system responses of young mice (2 to 3 months old) and old mice (equivalent of 70- and 80-year-old humans) to bacterial infections, the researchers discovered that as mice age, they lose microphages.

Those are a type of cell that fights infecting bacteria. In conjunction with other cells, they form the front lines of the immune system. But as both people and mice grow old, their immune systems change: Infections come more often and with greater intensity.

Medina believes that keeping the immune system working longer and better can help people live longer, healthier lives. "Since the immune system protects our body against infections, to keep the immune system young and functional is a crucial factor for healthy aging," she says.

Her team looked at the reactions of young and old mice to Streptococcus pyogenes, which is probably best known for causing strep throat. But it can also cause life-threatening infections like impetigo, scarlet fever and cellulitis, especially in elderly people. While the young mice were able to fight off the invading bacteria, the older mice - even those infected with fewer bacteria - died.

Later, the researchers studied the differences in the immune systems of the young mice and their older counterparts. They found that the aged mice had fewer microphages in their tissue than the younger ones.

The team treated the older mice with the specific protein that affects microphage counts to see if it could increase their ability to ward off infections. They found that the repeated preventive treatment did help them maintain their microphages and efficiently fight infective bacteria — a result that may help the elderly stave off disease.

While their research certainly won't help Grandma look like she's 20 again, it may help her immune system act like it.

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