Autoimmune disorders arise from an inappropriate immune response against substances and tissues normally present in the body. They are broadly grouped into two categories: organ-specific disorders (Hashimoto thyroiditis, Addison disease, pernicious anemia, etc.) and non-organ-specific disorders (systemic lupus erythematosus, Sjogren syndrome, rheumatoid arthritis, scleroderma, etc.).
Autoimmunity is a condition in which immune system of the body fails to recognize between ‘self’ and ‘non-self ’ and reacts by formation of antibodies against own tissues.
The condition maybe limited to one of the organ like in Goodpasture syndrome or may be may involve specific tissues of different organs like in systemic lupus erythematosus. Clinical symptoms depend on the type of tissue involved. Diagnosis is always done by the detection of autoantibodies against specific tissue and histopathology. Immunosuppressant drugs are important treating agent in these conditions .
The reason that body fails to recognize between ‘self’ and ‘non-self ’may be immunologic, genetic or microbial. Mixed etiology may be possible. There is polyclonal activation of B-cells along with generation of self reacting B-Cells. This may be augmented by increased T helper cell activity. Genetic factors include increased expression of Class II HLA antigens on affected tissues. Infection with virus like Epstein–Barr virus (EBV) or bacteria like streptococcus and mycoplasma may trigger immune reaction against host tissue .
In the United States autoimmune conditions are among the leading causes of death among women of young and middle-age. Incidence rates differ according to disease. Less than one case of systemic sclerosis is diagnosed per 100,000 person years whereas more than 20 cases of adult-onset rheumatoid arthritis are diagnosed per 100,000 person-years. Diseases like type I diabetes primarily occur in childhood and adolescence whereas myasthenia gravis or multiple sclerosis occurs in the mid-adult years. Rheumatoid arthritis, primary systemic vasculitis are diagnosed among older adults .
Once autoantibodies are formed against own tissue there may be one of four actions, i.e. anaphylactic, cytotoxic, immune complex or cell mediated. Anaphylaxis is characterized by releasing histamine locally or generally. Examples are asthma, hay fever and serum sickness. Examples of cytotoxic reaction are autoimmune hemolytic anemia, transfusion reaction, erthrobalstosis foetalis, idiopathic thrombocytopenic purpura (ITP) and myasthenia gravis. Examples of immune complex reaction are farmer’s lung, glomerulonephritis, collagen disease, Goodpasture syndrome and arthritis. Cell mediate reactions are leprosy and graft rejection .
Autoimmune diseases are chronic, characterized by remission and relapse or flare up. But clinical symptoms are well controlled by treatment .
Symptoms depend on type of reaction due to autoimmunity and its site. The common symptoms are fatigue, fever, malaise, joint pain, and rash. Anaphylaxis is characterized by dizziness, rash itching, breathless, tachycardia and lip swelling. Autoimmunity against blood components is characterized by fatigue, yellow urine, and fever. Involvement of lung is characterized by cough, fever and dyspnea .
The diagnosis can be done by physical exam and laboratory investigation. Important laboratory tests are antinuclear antibody tests, autoantibody tests, complete blood cound (CBC), comprehensive metabolic panel, C-reactive protein (CRP), Erythrocyte sedimentation rate (ESR) and urinalysis.
Chest X-ray and pulmonary function test may be required in case of lung involvement. Similarly, bone marrow biopsy or kidney biopsy may be done if required.
Kidney function test and renal function test may be required in advanced cases or the cases taking treatment for long period or for the cases like graft rejection .
Symptomatic control, control of autoimmune reaction and maintainance of general immunity are the objectives of treatment. Mainstay of treatment is control of immune reaction by immunosuppressant drugs either corticosteroids like prednisone or non-steroids like tacrolimus, cyclophosphamide, sirolimus, mycophenolate or azathioprine. Further treatment depends on type of disease like hormones, hematinincs, blood transfusion or physiotherapy. Anaphylaxis is an emergency and requires prompt emergency services including oxygen, advanced life support measures, drugs like adrenaline .
Since etiology of autoimmunity is immune-genetic prevention of these diseases is not possible. Only conditions precipitated by bacterial or viral infections are preventable by control of these infections .