title: Comparison of two ELISA assays for anti-Sp100 determination.
abstract: Antibodies to Sp100 have been described not only in primary biliary cirrhosis (PBC), but also in other diseases. Two assays for detection of Sp100 levels by enzyme-linked immunosorbent assay (ELISA) have been compared in a cohort of patients from our area: (a) Sp100 kit produced by IMTEC, Immunodiagnostica GmbH, and (b) Quanta Lite Sp100 kit produced by INOVA Diagnostics. We analyze here the correlation between the two assays and compare their efficiency in diagnosing PBC. We also comment on the exceptions derived from reactivity with other diseases. We studied 78 sera by IIF with the typical multiple nuclear dots (MND) pattern from patients who suffered from PBC, hepatopathies different from PBC, systemic lupus erythematosus (SLE), other connective tissue diseases (CTD), skeletal diseases, lung diseases, hematological disorders, a miscellaneous group, and a healthy IIF negative control group. The tests work equally well despite their different quantification system: (a) it is based on a standard curve; and (b) it is based on a single-point antigen-specific calibration. Some discrepancies could be explained by differences in the immunodominant epitope used in the ELISA. The main finding of this study is that the presence of MND/Sp100-positive antibodies were detected not only in hepatic diseases, mainly PBC, but also in other clinical conditions, confirmed by both tests. Diagnosis of PBC must be established in the right clinical context, because other diseases recognizing the same epitope, mainly SLE, may also show high Sp100 levels. Sera from PBC patients with antimitochondrial antibodies (AMA) showed higher anti-Sp100 than the AMA-negative group.
authors.affiliation: Department of Immunology, Hospitales Universitarios Virgen del Rocío, Sevilla, Spain. jmlucenas@hotmail.com
authors.forename: José
authors.initials: J
authors.lastname: Manuel Lucena
authors.forename: Marcos
authors.initials: M
authors.lastname: Montes Cano
authors.forename: José
authors.initials: J
authors.lastname: Luis Caro
authors.forename: Nieves
authors.initials: N
authors.lastname: Respaldiza
authors.forename: Antonia
authors.initials: A
authors.lastname: Alvarez
authors.forename: Julio
authors.initials: J
authors.lastname: Sánchez-Román
authors.forename: Antonio
authors.initials: A
authors.lastname: Núñez-Roldán
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Wichmann
mesh_terms: D000906:Antibodies / Q000276:immunology*; D034961:Antigens, Nuclear / Q000097:blood* / Q000276:immunology*; D001324:Autoantigens / Q000097:blood* / Q000276:immunology*; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D008928:Mitochondria / Q000276:immunology; D009687:Nuclear Proteins / Q000097:blood* / Q000276:immunology*