Fig 4. Index plasma binding to STS-supernatant captured with PLL or coated directly onto ELISA plate wells.

ELISA plate wells were pre-coated with 500 ng/ml PLL, and then used to capture STS-supernatant at concentrations from 250 ng/ml to 2,000 ng/ml of DNA (left panel) or from 1 ng/ml to 1,000 ng/ml (right panel), or with buffer alone as control. Index plasmas were used at 1/800 dilution in the ELISA. The data points for the anti-dsDNA and anti-SSA index plasmas represent a single well. The data points for anti-RNP, anti-histone, anti-SSB and anti-Sm index plasmas are the average of two wells. Squares show data for STS-supernatant directly coated on the plate; circles show data for STS-supernatant captured by polymer.