The Immune System
How males and females fight--and succumb to--disease

One aspect of a woman's immune system—the production of antibodies to fight off invading viruses and bacteria—is more active than men's. Perhaps, this is designed to help women survive the perils of pregnancy and childbirth. Whatever the reason, the result is that the heightened antibody activity allows women's bodies to mount a more vigorous battle against infectious viral and bacterial diseases such as hepatitis, E. coli infection, rubella (measles), brucellosis (a bacterial infection that can be transmitted through unpasturized diary products). In addition, the female immune system wages war more effectively against parasites.

There are disadvantages to this enhanced activity, however: Women are far more susceptible to immune system abnormalities that trigger autoimmune diseases, such as lupus and diabetes, than men are. Nine females are afflicted with systemic lupus erythematosus (SLE) for every male; for Sjogren's syndrome (a disorder that causes dry mouth and eye irritation) this ratio is 10:1; for rheumatoid arthritis (RA) it is 7:1; and the ratio is 2:1 for multiple sclerosis.

Female hormone fluctuations also have an impact on these autoimmune disorders: Premenstrual flare-ups of SLE and RA are common and both diseases are associated with abnormalities in the production and/or metabolism of sex hormones. Pregnancy lessens the symptoms of RA, but, during the first trimester, it intensifies the symptoms of lupus.

Source: The Partnership for Women's Health at Columbia. Stay tuned to this section of the site: More information on the influence of gender on the functioning of the immune system will appear over the next weeks and months.