Why do women generally live longer than men? A research result shows that women's immune systems age slower, which may be a major advantage in extending their lifespan. Japanese researchers reported on May 15th in the British journal "Immunology and Aging" that they tracked the blood levels of 356 healthy men and women aged 20 to 90, particularly the changes in immune related white blood cells and cytokines levels as they aged. It was found that although the total number of white blood cells decreases during the aging process, the decrease rate of lymphocytes such as T cells and B cells in male white blood cells is significantly faster than that in females, and both of these cells are related to resisting bacterial infections. During the aging process, women also perform better than men in terms of immune related cytokines and other immune parameters. Professor Katsuyuki Hirokawa from Tokyo Medical and Dental University, who led this study, said that estrogen helps with the production and regulation of lymphocytes, thereby affecting the immune system. This may be one of the reasons why women's immune systems age slower than men's. Researchers say that it is a common phenomenon for women to live longer than men. Previous studies have explained this phenomenon through differences in mitochondrial genes, but this study explains this phenomenon from the perspective of the immune system. It is reported that Japanese women have an average life expectancy of nearly 6 years longer than men, while the average life expectancy difference between men and women in the UK is 3 years. For detailed articles, please refer to immunity&aging http://www.immunityageing.com/content/10/1/19