Table II.

Production of IFN-α by normal PBMC cultured with pcDNA3 in combination with IgG prepared from SLE or control serum

Serum IgGaInduced IFN-α (U/ml)b
Without primingWith priming
No pcDNA3pcDNA3Meth. pcDNA3No pcDNA3pcDNA3Meth. pcDNA3
SLE 1<21504 ± 527<2186 ± 165143 ± 687111 ± 34
SLE 2<2220 ± 18<2255 ± 172322 ± 248121 ± 10
SLE 3<21296 ± 320<2171 ± 304792 ± 467124 ± 62
SLE 4<2153 ± 27<211 ± 52072 ± 14535 ± 26
SLE 5<2<2<211 ± 1344 ± 2615 ± 8
SLE 6<23 ± 1<22 ± 537 ± 1411 ± 5
SLE 7<23 ± 4<215 ± 9189 ± 10219 ± 6
SLE 8<26 ± 2<25 ± 2320 ± 2714 ± 10
SLE 9<23 ± 11<218 ± 11248 ± 7718 ± 12
NS 1<2<2<2<295 ± 17<2
NS 2<23 ± 1<2<2128 ± 25<2
NS 3<2<2<2<2<2<2
NS 4<2<2<2<2169 ± 15<2
Medium<2<2<2<22 ± 4<2

  • a The IgG was obtained by DNAse I treatment of serum obtained from nine SLE patients (SLE 1–9) and four normal individuals (NS 1–4), followed by separation on protein G-Sepharose columns.

  • b The PBMC were cultured for 24 h with serum IgG (1 mg/ml) combined or not with the normal or methylated (meth.) plasmid pcDNA3 (0.5 μg/ml), and with or without IFN-α priming (500 U/ml). The cultures were in triplicates and concentrations of induced IFN-α in culture supernatants (mean ± SD) were determined by immunoassay. Results from one of two experiments with similar results are shown.