Table 3.

Keratinocytes from lupus patients show enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) with anti-SS-A/Ro antibody

†Antibody specificity: pooled sera specific for anti-SS-A/Ro, anti-ssDNA and pooled normal human sera (NHS) were fractionated; the IgG-enriched fractions were used as antibody-enriched reagents. The anti-SS-A/Ro reagent showed largely anti-60-kD activity blocked by competition with purified SS-A/Ro.‡ADCC of irradiated targets = (T_UVRAE − T_UVRE) − (TAE − TE), where T_UVR are targets irradiated with UVB 24 h before the experiment was performed, and T are keratinocytes which were sham-irradiated. The enriched sera are the antibody (A) source and the effectors (E) are homologous mononuclear effectors. The irradiated keratinocytes were exposed to 100 mJ/cm² UVB.Values represent the mean percentage cytotoxicity and 1 s.d.Irradiated targets incubated with anti-SS-A/Ro antibody did show some cytotoxicity without added mononuclear effectors, but it represented only a fraction of the cytotoxicity observed with antibody plus effectors (data not shown).Statistical significance: *P < 0.005 (versus anti-SS-A/Ro plus adult control keratinocytes), P < 0.025 (versus anti-SS-A/Ro plus discoid lupus erythematosus (DLE) keratinocytes), P < 0.05 (versus NHS plus systemic lupus erythematosus (SLE) keratinocytes); **P < 0.025 (versus anti-SS-A/Ro plus adult control keratinocytes; ***P < 0.025 (versus NHS plus DLE keratinocytes); ****P < 0.001 (versus anti-SS-A/Ro plus adult control keratinocytes), P < 0.05 (versus anti-SS-A/Ro plus DLE keratinocytes); *****P < 0.025 (versus anti-SS-A/Ro plus adult control keratinocytes), P < 0.05 (versus anti-SS-A/Ro plus DLE keratinocytes).