Fig. 2

Influence of serum on MP-induced ROS production by SLE PMNs. Purified leukocytes from eight SLE patients, six of whom had SLEDAI > 5, were incubated with DHR and stimulated for 30 min at 37 °C with autologous MPs alone or in combination with LPS, or with PMA, in a medium containing 25% v/v autologous serum or a pool of NHS. The resulting ROS production by PMNs was analysed by flow cytometry, and the ratio between median fluorescence intensity (MFI) values obtained in the presence of SLE serum above that obtained in the presence of NHS was calculated after adjustment for background (unstimulated cells). Ratios from three experiments were excluded because either the numerator or denominator was negative. (a) Ratios between MFI values observed after stimulation with MPs and LPS in the presence of autologous serum above that observed in the presence of NHS. Bars represent median ratios. (b) Correlation between the ratio and circulating levels of C3 in samples stimulated with a combination of MPs and LPS. Dotted line represents the lower limit of the normal range. LPS lipopolysaccharide, MP microparticle, PMA phorbol-12-myristate-13-acetate, SLE systemic lupus erythematosus, Unstim unstimulated