ANCA antibody with peripheral rim distribution is indicative of
Correct Answer: Anti double stranded DNA antibody
Description: Ref 9/e p219,8/e p214,7/e 228 Antinuclear antibodies. ANAs are directed against several nuclear antigens and can be grouped into four catego- ries: (1) antibodies to DNA, (2) antibodies to histones, (3) antibodies to nonhistone proteins bound to RNA, and (4) antibodies to nucleolar antigens. Table 4-10 lists several autoantibodies, including ANAs, and their asso- ciation with SLE as well as with other autoimmune dis- eases, to be discussed later. The most widely used method of detecting ANAs is the indirect immunofluo- rescence assay (IFA), which screens for autoantibodies that bind to a variety of nuclear antigens, including DNA, RNA, and proteins. Four staining patterns are seen with IFA: homogeneous or diffuse, rim or periph- eral, speckled, and nucleolar. While each pattern can be suggestive of the presence of specific autoantibodies, the strength of these associations is limited and should not be relied on. ANA testing by IFA is extremely sensitive, as more than 95% of patients with SLE will test positive, but the test's specificity is quite limited, because patients with other autoimmune diseases, chronic infections, and cancer will test positive as well. Fuhermore, ANAs are seen in approximately 5% to 15% of healthy people, and the incidence increases with age. Recently, the IFA has been replaced in many clinical laboratories by multiplex flow cytometry immunoassays that can simultaneously test for multiple specific autoantibodies, but these assays may lack the sensitivity of the IFA. Antibodies to double- stranded DNA (dsDNA) and the so-called Smith (Sm) antigen can be detected by ELISA or multiplex flow methods and are specific for SLE. * Other autoantibodies. Antibodies against blood cells, including red cells, platelets, and lymphocytes, are found in many patients. Antiphospholipid antibodies are present in 40% to 50% of patients with lupus and react with a wide variety of proteins in complex with phospholipids. Some bind to cardiolipin antigen, used in serologic tests for syphilis, so patients with lupus may have a false-positive test result for syphilis. Antiphos- pholipid antibodies contribute to coagulation abnormal- ities,
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