Lupus and Lupus Kidney Disease - Kidney Disease - What causes Lupus?
More details about the immune system...
The usual job of the immune system is to fight invaders into the body. These might be germs or bugs, or foreign objects such as splinters. The body recognises these invaders and tries to eliminate them from the body. The blood contains two main types of defence system. One is white blood cells, which stick to germs and kill them. The other type of defence is antibodies, which are smaller than the white blood cells. They work by sticking onto germs and either make them burst apart, or help the white blood cells to stick to them.
The immune system is very powerful and is normally very good at recognising what is part of the body and what is not. However, sometimes it makes a mistake and attacks the body as if that part of the body was an invader. There are many different diseases caused by the immune system, and they can affect any part of the body. There are several kidney diseases caused by the immune system. Some of them affect only the kidneys, some can affect other parts of the body as well as the kidneys.
It is not clear why the immune system causes diseases such as Lupus. There may be some trigger that makes the immune system go wrong, such as an infection. It is not known why Lupus occurs, except in the extremely rare cases where Lupus is a side effect of a drug.
Lupus can occasionally occur in more than one family member, and is more common in people who are black, Hispanic or Asian than in Europeans. There is no scientific explanation for this at the present time.
More details on the antibodies that cause Lupus...
Antibodies are not all the same. Our blood contains millions of different antibodies, each one directed against only one type of chemical invader. Blood tests can measure several different types of antibody in Lupus patients which are not normally present in the body. These antibodies can attack the normal tissues of the body, instead of invaders. The most important are antibodies against double stranded DNA (called anti-dsDNA antibodies for short), and an antibody called anti-cardiolipin.
Anti-ds DNA antibodies (anti-double stranded DNA). These are the most important antibodies in Lupus. DNA is the chemical inside our cells that is the code for life. Antibodies against the centre, or nucleus of the cells in our body, are very common and usually do not cause problems, but antibodies against double stranded DNA (called anti-dsDNA) do seem to be important if they are present. Nearly everyone with Lupus has anti-dsDNA antibodies, so it is an important test. Also, the amount of the antibody in the blood can be measured, and is useful in many people as a measurement of disease activity. The anti-dsDNA antibody level can therefore help to calculate the correct amount of drug treatment someone with Lupus should receive.
Anti-cardiolipin antibodies (also called anti-phospholipid antibodies). These are important in Lupus because someone with this antibody is at risk of blood clots and women are at risk of miscarriage if they get pregnant. Not everyone with these antibodies will run into trouble, but if someone with Lupus wants to have a baby or has a history of blood clots, this test should be performed. If these antibodies are present, they do not usually go away with treatment, so that some people may need long term treatment to prevent blood clots. This usually means drug treatment to make the blood clot less well (anticoagulation). Warfarin tablets are most commonly used, but because warfarin can harm a baby, heparin injections are used during pregnancy. Milder cases may be able to take aspirin to reduce the chances of blood clots.
Anti-nuclear antibodies. The nucleus is the central part of each cell in our body, and antibodies against the nucleus are quite common. Anti-nuclear antibodies do not mean someone has Lupus - it is necessary to go on and do other tests such as anti-dsDNA antibodies to confirm a diagnosis of Lupus.
Anti-Ro and anti-La antibodies. These may also be present in Lupus. They may help confirm a diagnosis of Lupus if the anti-dsDNA antibodies are not present. Also, anti-Ro antibodies can cause problems in pregnancy, and should be tested if a woman with Lupus wants to have a baby.
Crithidia antibodies. This is a very sensitive test for anti-dsDNA antibodies. It is used to confirm a diagnosis of Lupus in difficult cases, but does not have value in monitoring the effects of treatment.
The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.