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Study: Women live longer than men as their immune systems age more slowly

By Catholic Online (NEWS CONSORTIUM)
May 15th, 2013
Catholic Online (www.catholic.org)

According to a new study, the reason women live longer than men partly because their immune systems age more slowly, a new study has revealed. While men in both the United Kingdom and Japan have a life expectancy of 79, women are expected to live as long as their early eighties.

LOS ANGELES, CA (Catholic Online) - The study, led by Professor Katsuiku Hirokawa, from Tokyo Medical and Dental University, found that "age-related changes in various immunological parameters differ between men and women. Our findings indicate that the slower rate of decline in these immunological parameters in women than in men is consistent with the fact that women live longer than do men."

In short, as their body defenses weaken with the passing years, the increasing susceptibility of men to disease shortens their lives.

The study, as conducted by Professor Hirokawa, involved examining blood samples from healthy volunteers with a wide range of ages. Researchers tested the blood of 356 men and women aged between 20 and 90 years of age and looked at levels of white blood cells and immune system signaling molecules called cytokines.

In both men and women, the number of white blood cells per person decreased with age. A closer study revealed striking differences between men and women. The rate of decline of most T-cell and B-cell lymphocytes, two key elements of the immune system, was faster in men.

Similarly, men showed a more rapid age-related decline in the two cytokines, IL-6 and IL-10.

CD4 T-cells and natural killer (NK) cells, two specific types of immune system cell that actively destroy foreign invaders, increased in number with age. The rate of increase was higher in women than in men. This is a significant find, as NK cells are believed to be one of the body's first lines of defense against cancer.

Inflammation is a potentially damaging immune system response that contributes to heart and artery disease and may play a role in dementia.

Its faster decline in men suggests that as men age, they might more rapidly be affected by inflammatory conditions.

"The process of ageing is different for men and women for many reasons," Professor Hirokawa says. "Women have more estrogen than men which seems to protect them from cardiovascular disease until menopause. Sex hormones also affect the immune system, especially certain types of lymphocytes.

"Because people age at different rates, a person's immunological parameters could be used to provide an indication of their true biological age."

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