Systemic lupus erythematosus (SLE), like Sjögren’s syndrome, is a type of autoimmune connective tissue disorder that may have both genetic and environmental causes. Connective tissue disorders are chronic inflammatory autoimmune disorders affecting the connective tissues. All connective tissues, i.e. joints, muscles, skin and blood vessels can be affected and therefore the disorders have multiple effects on many different organs throughout the body. They may develop slowly over many years, or they may present abruptly and show rapid progression. There are more than 200 different disorders affecting connective tissues, including SLE, Sjögren’s syndrome, scleroderma and mixed connective tissue disease. The presence of autoantibodies in the serum of patients is a very typical phenomenon for connective tissue disorders. Most of the autoantibodies are not specific and can be detected in patients with different diseases. However, in some cases, autoantibodies occur specifically in a certain disease and can aid in the diagnosis. Systemic lupus erythematosus (SLE or lupus), is a systemic autoimmune disease (or autoimmune- connective tissue disease) that can affect any part of the body. As occurs in other autoimmune diseases, the immune system attacks the body's cells and tissue, resulting in inflammation and tissue damage. The disease is nine times more common in women than in men. The disease can affect all ages but most commonly begins from 20-45 years of age. There seems to be an ethnic factor as lupus is somewhat more frequent in African Americans and people of Chinese and Japanese descent.
Indications: Diagnosis or follow-up of systemic lupus erythematosus (SLE). Pathogenesis: Being a systemic disease, SLE often involves a number of organs such as the heart, joints, skin, lungs, blood vessels, liver, kidneys, and nervous system. When only the skin is involved, the condition is called lupus dermatitis or cutaneous lupus erythematosus. A form of lupus dermatitis that can be isolated to the skin, without internal disease, is called discoid lupus. The skin rash in discoid lupus is most commonly found on the face and scalp. Over time, 5%-10% of those with discoid lupus may develop SLE. When internal organs are involved, the condition is referred to as systemic lupus erythematosus.The course of the disease is unpredictable, with periods of illness (called flares) alternating with remissions.
The age of onset of SLE is 20-40 years of age and it affects women nine times as often as men. The prevalence is about 40 cases per 100 000 people. The disease is chronic but there are relapses with relatively symptomfree intervals. Inflammation and organ damage occur in different parts of the body as a result of deposition of immune complexes with accompanying complement activation. The link to MHC is strong and there are indications of disorders of the apoptosis and the removal of apoptic material. This may result in immunogenic nucleosomes that can activate B and T lymphocytes. The disease may present as arthritis, hypersensitivity to the sun, discoid rashes, butterfly exanthema, cold sores, serositis, renal failure, neurological symptoms, cytopenias, myalgia, myositis or other clinical symptoms like Raynaud’s phenomenon, alopecia, vasculitis, lung and heart symptoms. The etiology remains unknown. The American College of Rheumatology has published diagnostic criteria for SLE. Four out of eleven must be met. Two criteria include autoantibodies: 1. AntidsDNA of an elevated level or anti-Sm or anti-cardiolipin IgG or IgM; 2. Elevated level of ANA with IIF without the patient taking medicine that may cause syndromes similar to those of lupus. If there is a clinical suspicion of SLE, the investigation usually starts with ANA. This test has a sensitivity of around 95% but with a low specifi city. This means that the clinical signifi cance of a positive ANA in patients with few symptoms is low. Anti-dsDNA seldom occurs in healthy people and is practically pathognomonic for SLE. It occurs in 50-80% of untreated patients with SLE. It is interesting to find that in several studies the level of the antibody has been shown to vary with disease activity. A high level often correlates with lupus nephritis. An increasing level may also predict relapses of SLE nephritis, whereas a declining level is consistent with reduced disease activity. It is therefore important to follow the level during the treatment of lupus nephritis Anti-Sm antibodies have a very high diagnostic value, as they have a high specificity but a low sensitivity. A number of other antibodies occur in SLE and among the more common ones is SSA/B, which may be important to analyze if there is a risk of congenital heart block, especially the 52kD protein and the SSA p200 peptide, see p. 23. Anti-histone antibodies are also common, especially in drug induced lupus.
The disease is chronic but there are relapses with relatively symptomfree intervals. Inflammation and organ damage occur in different parts of the body as a result of deposition of immune complexes with accompanying complement activation. People with SLE can develop a large number of symptoms and often in combinations. Common complaints and symptoms include fatigue, low-grade fever, loss of appetite, muscle aches, arthritis, ulcers of the mouth and nose, facial rash (the classical "butterfly rash"), sensitivity to sunlight, pleuritis pericarditis, and Raynaud's phenomenon (poor circulation to the fingers and toes with cold exposure). Complications of organ involvement can lead to further symptoms depending on the organ affected and/or severity of the disease. Over half of the people with SLE develop a characteristic red, flat facial rash over the bridge of their nose. Because of its shape, it is frequently referred to as the "butterfly rash" of SLE. Most people with SLE will develop arthritis during the course of their illness. Arthritis in SLE commonly involves swelling, pain, stiffness, and even deformity of the small joints of the hands, wrists, and feet. Sometimes, the arthritis of SLE can mimic that of rheumatoid arthritis. More serious organ involvement with inflammation occurs in the brain, liver, and kidneys. White blood cells and blood-clotting factors also can be characteristically decreased in SLE, known as leukopenia and thrombocytopenia, respectively. Leukopenia can increase the risk of infection, and thrombocytopenia can increase the risk of bleeding. Other sites of inflammation related to SLE are muscles (myositis), blood vessels (vasculitis), and the kidneys. Kidney inflammation may lead to end-stage disease with complete renal failure requiring dialysis. Involvement of the brain can cause personality changes, thought disorders (psychosis), seizures, and even coma. Brain involvement is commonly referred to as lupus cerebritis. Since individuals with SLE can have a wide variety of symptoms and different combinations of organ involvement, accurate differential diagnosis is difficult. As it is, no single test establishes the diagnosis of systemic lupus. The American College of Rheumatology has issued 11 criteria to facilitate the diagnosis of SLE.