Fig. 1.

Establishing the modified Lancefield assay conditions. A) IdeS is inhibited by A484. 2 μg of IVIG (all lanes) was incubated with 0.5 μg of IdeS in presence of 10 mM iodoacetamide (IAM), 10 mM A484 or PBS. Reactions were visualised by SDS-PAGE under non-reducing conditions. Molecular mass markers are given in kilodaltons. B and C) IdeS can reduce the anti-streptococcal activity of whole blood but not in the presence of A484. Plasma from B) IdeS treated or C) IdeS/A484 treated blood samples (n = 3) were evaluated for anti-streptococcal activity by ELISA. Grey shading represents the upper and lower OD₄₅₀ values from wells incubated with PBS in place of plasma. Data: mean ± SD. D) Evaluation of A484 impact on human neutrophils. Donor neutrophils (n = 3) were incubated with PBS (white bars), 2.5 mM A484 (grey bars) or 2.5 mM iodoacetamide (black bars) for 4 h, and the percentage of live, apoptotic and dead neutrophils was determined by flow cytometry following FITC-annexin V/PI staining. Data: mean ± SD. *p < 0.05, two-way ANOVA with Bonferroni's correction.