Fig 3. The effect of PLL on ANA assays using supernatant of apoptotic cells as antigen.

ELISA plate wells were pre-coated with 2 μg/ml PLL, and then used to capture STS-supernatant at concentrations from 1 ng/ml to 2,000 ng/ml of DNA or buffer alone as control; the concentration refers to that of DNA. The same concentrations of STS-supernatant were coated to plate wells without polymer pre-coat. Binding by antibodies in three SLE plasmas was assayed in a standard ELISA assay. Points shown are the average OD₄₅₀ of two wells. Squares show data for STS-supernatant directly coated on plate; circles show data for STS-supernatant captured by polymer. (A) Binding by SLE plasma 1 at 1/1,600 dilution; (B) Binding by SLE plasma 2 at 1/1,600 dilution; and (C) Binding by SLE plasma 3 at 1/800 dilution.