Action of Ps82 on the complement pathways.

<p>Samples (50 μL) of normal human serum (NHS) were pre-incubated with 0.25, 0.33 or 0.5 μg/mL of Ps82 or with 175 μg/mL of the <i>Premolis semirufa</i>’s bristles extract. The mixtures were pre-incubated for 30 min for the alternative pathway <b>[A]</b> or 1 h for the classical pathway <b>[C]</b> at 37°C, and then assayed for the residual complement activity in haemolytic tests. For lectin pathway <b>[B]</b>, samples of 50 μL of NHS were pre-incubated, in the presence or absence of 10 mM 1,10-Phenanthroline, with 0.5 μg/mL of Ps82 or 175 μg/mL of the <i>Premolis semirufa</i>’s bristles extract for 30 min at 37°C and then evaluated for the residual complement activity by ELISA. Alternatively, samples of NHS incubated with Ps82 or the <i>Premolis semirufa</i>’s bristles extract were evaluated in conditions for activation of the classical pathway, by the deposition of complement component C4b by ELISA <b>[D]</b>. Data are representative for three separate experiments, performed in duplicate, and the results are expressed as percentage of haemolysis (%) ± SD (for A and C) and percentage of C4b deposition (%) ± SD (for B and D) in relation to the control samples (NHS + buffer) and between the treatments. (*) <i>p</i> < 0.05 (**) <i>p</i> < 0.01 and (***) <i>p</i> < 0.001. The symbol (#) indicates significant differences between the extract and Ps82.