Quantifying Complement System Activation

Pooled serum from healthy donors (cod A113, Quidel, Corporation, CA, USA) and individual serum samples derived from healthy donors as well as from patients suffering from diseases such as immunodeficiency, allergy and cancer (In.Vent, Germany) were aliquoted and stored at − 80°C until further analysis. Additional information on clinical parameters of human serum obtained from both healthy donors (n_healthy=32 donors) and patients with preconditions (n_allergy=26, n_{immunodeficinecy}=16; n_cancer=15) are presented in the Supplements Table S2. Heat Aggregated Gamma Globulin (HAGG; cat. A114) and Cobra Venom Factor (CVF; cat. A600) were purchased from Quidel (Santa Clara, CA, USA) while Zymosan A (CAS 58856–93-2) was purchased from Sigma Aldrich (Italy) to be used as positive controls for the activation of the complement system. The induction of iC3b levels were quantified with a commercially available Microvue Enzyme-linked Immunosorbent Assay kit (cat. A006, Quidel, Corporation, CA, USA) following manufacturer’s instructions.