Studying genes for complement, a series of proteins in the blood that play an important part in the immune system, is another active area of lupus research. Complement acts as a backup for antibodies, helping them destroy foreign substances that invade the body. If there is a decrease in complement, the body is less able to fight or destroy foreign substances. If these substances are not removed from the body, the immune system may become overactive and begin to make autoantibodies.
Identifying genes that play a role in the development of lupus is an active area of research.
Recent large studies of families with lupus have identified a number of genetic regions that appear to be associated with risk of SLE. Although the specific genes and their function remain unknown, intensive work in mapping the entire human genome offers promise that these genes will be identified in the near future. This should provide knowledge of the complex factors that contribute to lupus susceptibility.
NIAMS-funded researchers are uncovering the impact of genetic, socioeconomic, and cultural factors on the course and outcome of lupus in Hispanics, African Americans, and Caucasians. Preliminary data show that African American and Hispanic lupus patients typically have more kidney damage compared with Caucasians. In addition, NIAMS-funded researchers found that African American lupus patients have more skin damage compared with Hispanics and Caucasians, and that the death rate from lupus is higher in African Americans and Hispanics compared with Caucasians.
It is thought that autoimmune diseases, such as lupus, occur when a genetically susceptible individual encounters an unknown environmental agent or trigger. In this circumstance, an abnormal immune response can be initiated that leads to the signs and symptoms of lupus. Research has focused on both the genetic susceptibility and the environmental trigger. Although the environmental trigger remains unknown, microbial agents such as Epstein-Barr virus and others have been considered. Researchers also are studying other factors that may affect a person's susceptibility to lupus. For example, because lupus is more common in women than in men, some researchers are investigating the role of hormones and other male-female differences in the development and course of the disease. A current study funded by the NIH is focusing on the safety and effectiveness of oral contraceptives (birth-control pills) and hormone replacement therapy in women with lupus. Doctors have worried about the wisdom of prescribing oral contraceptives or estrogen replacement therapy for women with lupus because of a widely held view that estrogens can make the disease worse. Oral contraceptives and estrogen replacement therapy do not, as once feared, appear to intensify lupus symptoms. Scientists do not know the effects of oral contraceptives on women with antiphospholipid antibody syndrome.