Table 1. The effect of DNase digestion on the antigenic activity of the supernatant.

		STS			% Reduction
	ELISA	supernatant	OD450	OD450	of OD450
Plasma	format	ng/ml	Control	DNased	With DNase
SLE plasma 1	direct	2,000	0.769	0.781	0
SLE plasma 1	PLL captured	250	0.813	0.417	49
SLE plasma 2	direct	2,000	0.820	0.607	26
SLE plasma 2	PLL captured	250	1.007	0.277	73
SLE plasma 3	direct	2,000	0.485	0.409	16
SLE plasma 3	PLL captured	500	0.871	0.471	46
Anti-SSA	direct	2,000	0.757	0.645	15
Anti-SSA	PLL captured	500	1.112	1.070	4
Anti-SSB	direct	1,500	0.979	0.843	14
Anti-SSB	PLL captured	250	0.878	0.351	60
Anti-dsDNA	direct	2,000	0.515	0.435	15
Anti-dsDNA	PLL captured	1,000	1.055	0.424	60
Anti-histone	direct	250	2.162	2.134	1
Anti-histone	PLL captured	5	0.861	0.743	14
Anti-RNP	direct	500	1.885	1.900	0
Anti-RNP	PLL captured	25	1.100	0.534	51
Anti-Sm	direct	250	1.704	1.730	0
Anti-Sm	PLL captured	100	1.042	0.860	17

The effect of DNase treatment of the STS-supernatant was examined using both the direct coat and the PLL capture ELISA formats. STS-supernatant was DNased for 1h with 40 Kunitz units/ml DNase I. A range of concentrations of untreated STS-supernatant and identically diluted DNased supernatant was coated directly to plates, or captured in wells with PLL, and then examined by ELISA using 1/800 dilution of SLE or index plasmas. STS-supernatant concentration refers to the PicoGreen DNA content of the untreated control. Data shown are for the concentration tested for which the OD₄₅₀ of the untreated STS-supernatant was closest to 1.0. Percent reduction upon DNasing was computed (see text). Cases where signal was higher for DNased supernatant than for untreated supernatant are reported as 0.