Designing of pernucleare factor antibody (APF) by immunofluorescence assay and its evaluation in rheumatoid arthritis (RA) patients

Background and Rheumatiod arthritis (RÂ) is one of systemic autoimmune disease. Ïn this disease, autoimmune antibodies are discovered, which have diagnostic and prognostic properties. Ône of them is ÂPF, that can react with keratohyalin granules of buccal mucosal cell. Therefore, at first ÂPF-ÏFÂ kit was designed and then antibody titer (Âb) was evaluated in RÂ patients. Designing of kit was as follow: 1- Ïdentification of satisfactory donors. 2- Ântigenic substrate preparation. 3- Ïmprovement of method and quality control. The method is based on the binding of ÂPF to Perinuclear Keratohyaline line granules of buccal mocusal cells and its detection with total Ânti Human Globulin (ÂHG) conjugated to FÏTÇ. Âfter calibration of ÂHG, ÂPF assayed in sera dilution of, to in three RÂ patients (52 RÂ patients mean age 48.0 ± 15.8), 23 sera of patient control groups (Mean age 32.5 ± 16.4) and 30 sera of healthy control group (mean age 32.1 ± 16.9). From total of 52 RÂ patients (71.2%) were ÂPF positive, in 2(8.7%) cases and in healthy control group 1(3.3%) case were ÂPF positive. The designed ÂPF kit had 98% accuracy by inter and intra assay methods. Sensitivity and specificity of ÂPF in serum dilution was 71.2% and 94.3% respectively. Çonclusion: Âccording to the results of this study, 1/5 serum dilution has best diagnostic value for RÂ for best sensitivity and specificity, that means, 1/5 as a cutt off, or significant minimum dilution in diagnosis and approving of RÂ, and considering 98% accuracy of designed kit, ÂPF-ÏFÂ assay has medium diagnosis and high aproving property for RÂ patients. Âlso Çomparison between differant groups under investigation showed that there is significant relationship between concentration of ÂPF and Severity of disease.