Table 1.

Method of determination for serological tests in SLE

Routine serological test	Method of determination
Anti-nuclear antibodies (ANA)	Indirect immunofluorescence. ANAs were considered positive if the titre was >1/80. Anti-double-stranded DNA (dsDNA) antibodies were measured by standard ELISA and defined as positive if more than twice the upper limit of normal (50 IU/mL on three occasions) or if positive by a Crithidia luciliae test.
Anti-cardiolipin (aCL) antibodies	Anti-cardiolipin was determined by ELISA and results were considered positive if medium-to-high titres (>20 IgG phospholipid units or IgM phospholipid units) were present on two or more occasions at least 6 weeks apart.
Lupus anticoagulant (LA)	Lupus anticoagulant activity was detected by coagulation assays (dilute Russell’s viper venom time) according to the guidelines of the International Society on Thrombosis and Hemostasis.
Anti-RNP antibodies	All by standard ELISA.
Anti-Ro/La antibodies
Anti-Sm antibodies
Anti-Ribosomal P antibodies
Rheumatoid Factor (RF)	Sheep cell agglutination. Rheumatoid factor was considered positive if the titre was >1/80.
C3 count	Laser nephelometer