Correlation between screening assay of antinuclear antibody and confirmatory assay of specific antibody

Abstract

Objective To investigate the correlation between screening assay of antinuclear antibody ( ANA ) and confirmatory assay of specific antibody. Methods Five hundred clinical patients' serum samples were detected by indirect immunofluorescence ( I1F) for screening assay of ANAs and line immunoassay ( LIA) for confirmatory assay of specific ANAs. According to the results of IIF-ANA and LIA-ANAs, 500 samples were divided into 4 groups; IIF-ANA ~+/LIA-ANAs~+ group, IIF-ANA~+/LIA-ANAs~-group, IIF-ANA~-/LIA-ANAs~+ group and IIF-ANA~-LIA-ANAs~- group. The samples in IIF-ANA~-VLIA-ANAs~+ group were collected and rechecked by ELISA and DID for detection of specific ANAs. Results Five hundred clinical samples were identified including 247 cases of IIF-ANA~+/LJA-ANAs~+86 cases of IIF-ANA ~+/LIA-ANAs~- , 152 cases of IIF-ANA~-/LIA-ANAs~- and 15 cases of IIF-ANA~- /LIA-ANAs~+, In IIF-ANA ~+/LIA-ANAs~+ group, 48. 2% ,23. 9% and 27. 9% patients had the titre of IIF-ANA 1:1 280, 1: 80-1:160 and 1:320-1:640. Fifteen cases of LJA-ANAs~+ were identified in 167 cases of HF-ANA(9. 0% ). Among 15 cases of IIF-ANA~-/LIA-ANAs~+ 11 positive cases were identified as anti-SSA and anti-Ro52 positive, which were rechecked by ELISA and DID, and the results were consistent with the prior detection. Other positive cases were identified including 1 case of anti-Histone, 1 case of anti-Scl-70, 1 case of anti-Jo-1 and 1 case of anti-AMA-M2. The positive consistent rates between LJA-ANAs and ELJSA, DID were 100% , 69% respectively. And 8 cases of IIF-ANA~-/LJA-ANAs~+ patients were diagnosed with autoimmune disease after clinical data analysis. Among 86 cases of IIF-ANA ~+ /LJA-ANAs~- , 50.0% and 36.1% patients had the titre of 1: 80-1: 160 and homogeneous fluorescence pattern respectively. There was a significant difference in IIF-ANA~+/LIA-ANAs~- group and IIF-ANA ~+/LIA-ANAs~+ (χ~2 =20.47,12.42, P<0. 05). Conclusions It is recommend that specific antinuclear antibodies can be used once screening assay of ANA is positive. But for clinically suspected AIDS patients, it is necessary to detect for specific antinuclear antibodies regardless of the result of screening assay of ANA. The confirmatory assay of specific antinuclear antibody could not replace the screening assay of antinuclear antibody. Key words: Immunofluorescence antibody technique; indirect; Antibodies; antinuclear; Autoimmune disease