Two specific types of immune system cell that attack invaders - CD4 T-cells and natural killer cells - increased in number with age, with a higher rate of increase in women than in men.

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And, by combining them harmoniously, you have the chance to really send powerful messages to your body, working on immune system, cell multiplication and differentation, metabolism, etc.

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For a T cell to become active, it must receive signals from another part of the immune system called an antigen-presenting cell.

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Medicare will not pay for all possible uses of Provenge, a cell therapy meant to prime the immune system to fight tumors.

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On April 28 Dendreon of Seattle notched Food and Drug Administration approval for Provenge, its cell therapy designed to train the immune system to fight prostate cancer.

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It neutralises potentially harmful oxygen molecules, boosts the immune system and rids the cell of toxins.

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"This is a stem cell that is generated by the body's own tissue so the immune system does not recognise it and they can get any place they want without being attacked, " said Prof Rambukkana.

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Pfizer found that a drug designed to harness the immune system to fight cancer was not effective in treating non-small-cell lung cancer.

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