title: Radioimmunoassay for anti-actin antibody: application in viral and autoimmune diseases.
abstract: The development of a non-competitive, solid-phase radioimmunoassay for quantitating anti-actin antibody is described. Anti-actin antibody was captured on BSA-coated microspheres of polystyrene to which a synthetic peptide representing the fifteen amino acid N-terminus of human beta-actin was covalently attached. A rabbit antiserum against the actin peptide fragment was used as reference serum for the assay. Serums of 23 out of 28 (82%) patients with chronic active hepatitis, shown to have anti-actin antibodies (range 2-140 micrograms ml-1) by immunofluorescence and immunoblot assays, were used to validate the radioimmunoassay. Only 7 out of 130 (5%) control subjects exhibited anti-actin antibody serum concentrations above 14 micrograms ml-1 (range 2-20 micrograms ml-1), the 95% confidence interval. Anti-actin antibody serum concentrations were determined to be elevated in 28 out of 47 (60%) patients with juvenile rheumatoid arthritis (range 5-89 micrograms ml-1), 43 out of 64 (67%) patients with human immunodeficiency virus infection and AIDS (range 3-80 micrograms ml-1), and 17 out of 23 (74%) infants with Kawasaki Syndrome (range 7-138 micrograms ml-1). All of the differences observed between patient groups, either singly or collectively, and the control group are highly significant (P less than 0.001) as judged by chi-square analysis. Since all of these disease states contain elements of viral infection and autoimmune disease, it is possible that viral infection in these diseases triggers the production of anti-actin antibody, possibly by means of molecular mimicry in response to viral oncogenes or to abnormal expression of actin in host tissue. This radioimmunoassay for anti-actin antibodies may prove to be a useful tool for the detection and monitoring of certain forms of autoimmune disease.
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030.
authors.forename: J E
authors.initials: JE
authors.lastname: McClure
authors.forename: W T
authors.initials: WT
authors.lastname: Shearer
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000097:blood; D000199:Actins / Q000276:immunology*; D000906:Antibodies / Q000032:analysis*; D001171:Arthritis, Juvenile / Q000097:blood; D001327:Autoimmune Diseases / Q000097:blood / Q000175:diagnosis*; D005455:Fluorescent Antibody Technique; D006521:Hepatitis, Chronic / Q000097:blood; D006801:Humans; D015151:Immunoblotting; D009080:Mucocutaneous Lymph Node Syndrome / Q000097:blood; D011863:Radioimmunoassay / Q000379:methods*; D014777:Virus Diseases / Q000097:blood / Q000175:diagnosis*
chemical_list: D000199:Actins; D000906:Antibodies