Fig. 3

MP-induced ROS production and degranulation of PMNs in the presence of heterologous sera. Leukocytes from a healthy blood group 0 donor were suspended in a medium containing 25% v/v of serum from 20 SLE patients and 10 healthy controls (see Table 1, frozen samples). DHR was used as probe for H₂O₂, and the cells were stimulated with autologous MPs in combination with LPS for 30 min at 37 °C before flow cytometry. (a) Median fluorescence intensity (MFI) after subtraction of background fluorescence (unstimulated cells). SLE patients were divided into two groups with circulating C3 levels > 1 g/l and ≤ 1 g/l, respectively. (b) Correlation between MFI values and anti-dsDNA antibody levels of patient sera. (c–e) Degranulation measured in the corresponding cell supernatants as the content of myeloperoxidase (MPO) from primary granules, neutrophil gelatinase-associated lipocalin (NGAL) from secondary granules and matrix metallopeptidase 9 (MMP-9) from tertiary granules. Bars represent median values. dsDNA double-stranded DNA, HC healthy control, SLE systemic lupus erythematosus