Atellica ch c3

IgG anti-dsDNA autoantibodies were quantified in serum samples by the commercial chemiluminescence immunoassay (CIA) (QUANTA Flash^®; Inova Diagnostics, San Diego, CA, USA) in the BIO-FLASH^® instrument (Biokit, Barcelona, Spain). The manufacturer’s recommended cut-off was used (20 IU/mL). Moreover, IgG anti-dsDNA autoantibodies were analysed by Crithidia luciliae indirect immunofluorescence test (CLIFT) (Inova Diagnostics, San Diego, CA, USA), with sera diluted 1:10. Results were reported as negative or positive (positive results were arbitrary ranged from 1 to 8 according to fluorescence intensity at fluorescence microscopy in comparison with a positive control (1:160) by trained personnel). The reference value is negative.
Complement (C3, C4) serum levels and activity (CH50) were measured by turbidimetric immunoassay (Atellica CH C3 and Atellica CH C4; Siemens, New York, NY, USA and Autokit CH50; Fujifilm Wako Chemicals, Neuss, Germany, all are tested in Atellica CH Solution, Siemens, New York, NY, USA). Reference values were: 0.870–1.700 g/L for C3, 0.110–0.540 g/L for C4 and 28–60 U/mL for CH50. Hypocomplementemia was considered when either CH50 activity or C3 or C4 levels were lower than reference values.