Researchers at led by Professor Katsuiku Hirokawa of the Tokyo Medical and Dental University analyzed blood samples from a group of 350 healthy men and women aged between 20 and 90 years. On analyzing the white blood cells and cytokines levels in the samples, the researchers found that while the white blood cells level declined with age in both the sexes, two key components of the immune system, known as T-cells and B-cell lymphocytes, declined slower in women compared to men.
The researchers also found that two types of immune system cells, known as CD4 T-cells and natural killer cells, which are responsible for attacking invaders increased faster in women compared to men.
"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 that in men is consistent with the fact that women live longer than do men", Professor Hirokawa said.