title: Characterization of anticytoplasmic antibodies in patients with systemic autoimmune diseases.
abstract: Abstract We characterized the cytoplasmic staining patterns identified by indirect immunofluorescence (IF) using human epithelial (HEp-2) cells as substrates, and identified autoantigens using enzyme-linked immunosorbent assay (ELISA) and cognate RNA immunoprecipitation techniques in cytoplasmic antibody-positive sera (CA(+)) in patients with systemic autoimmune diseases. Twenty-three sera (3.7%) of 630 patients were found to have a cytoplasmic staining pattern by IF on HEp-2 cells. The fine-pattern IF specificities were as follows: 12 diffuse fine speckled; 7 coarse granular filamentous speckled; 2 diffuse coarse speckled; 1 condensed large speckled; 1 cytoskeletal. No relationship was found between the staining patterns and the diseases. Anti-SS-A antibodies and antimitochondrial (M2) antibodies were detected by ELISA in 6 and 4 sera, respectively, and antismooth muscle antibody was detected by IF in 1 serum. In RNA immunoprecipitation assays, 6, 11, 3, and 1 patients had antibodies that recognized aminoacyltransfer RNA (tRNA) synthetases (including 2 EJ, 2 PL-7, 1 PL-12, and 1 unidentified tRNA-related), SS-A, ribosomes, and SRP, respectively. Moreover, several other autoantigens were detected by Western blotting using human epithelial (HEp-2) cell lysates. This study suggests that autoantibodies against tRNA synthetases, SS-A, ribosomes, mitochondria, and other autoantigens are present in CA(+) sera from patients with a variety of systemic autoimmune diseases.
authors.affiliation: First Department of Internal Medicine, Nagasaki University School of Medicine , 1-7-1 Sakamoto, Nagasaki 852-8501 , Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ida
authors.forename: Mingguo
authors.initials: M
authors.lastname: Huang
authors.forename: Ayumi
authors.initials: A
authors.lastname: Hida
authors.forename: Tomoki
authors.initials: T
authors.lastname: Origuchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kawakami
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Migita
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Tsujihata
authors.forename: Tsuneyo
authors.initials: T
authors.lastname: Mimori
authors.forename: Katsumi
authors.initials: K
authors.lastname: Eguchi