Immunology and Infection
Sex differences in male and female immune systems have major implications for disease. Almost all autoimmune diseases disproportionately affect women compared to men, and women are 75% more likely than men to suffer from rheumatoid arthritis, multiple sclerosis and lupus. Women are also twice as likely to contract a sexually transmitted disease and ten times more likely to contract HIV during unprotected sex with an infected partner.
Studies have also shown that, unlike men, women are often infected by multiple variants of the HIV virus, a finding that needs to be taken into consideration if development of an HIV vaccine is going to be effective for both men and women. If scientists develop a vaccine that only protects against virus variants found in men, women will still be vulnerable to infection.
Current methods of monitoring HIV patients also put women at a disadvantage. When a patient has HIV, doctors monitor the progression of the disease by testing his or her levels of CD4 lymphocyte, a particular immune cell that the virus attacks. A drop in CD4 levels is a major factor in a doctor’s decision to start a patient on highly active antiretroviral therapy (HAART) to prevent the onset of full-blown AIDS. However, women are more likely than men to develop and die from AIDS while still maintaining relatively high CD4 counts. Because of this, doctors are less likely to start women on HAART therapy in a timely fashion than they are their male counterparts.