Fig. 2: Amine-terminated PAMAM dendrimers trigger lectin pathway and amplification loop of the alternative pathway.

a sC5b-9 formation in plasma of nine human subjects on exposure to G5 amine-terminated PAMAM dendrimers. Plasma source (letter–number) = (gender–age). Three individuals were genetically deficient in MBL (MBL-def) (Supplementary Table 2). Open columns = background levels of sC5b-9, and grey columns = sC5b-9 levels on dendrimer incubation. b Incubation of G5 amine-terminated PAMAM dendrimers with MBL-deficient plasma reconstituted with MBL-MASPs (equivalent to 3 µg MBL mL⁻¹) elevates sC5b-9 levels. Human serum albumin was used as a negative control protein. c Mannan-coated wells induce fluid-phase sC5b-9 rises in MBL-def plasma on reconstitution with MBL-MASPs (equivalent to 3 µg MBL mL⁻¹). Open columns = controls (MBL-def plasma with added albumin), and grey columns = reconstituted MBL-def plasma with MBL-MASPs. In a–c, vertical numbers denote folds increases over their respective background. d The effect of anti-C1s monoclonal antibody (100 µgmL⁻¹) and futhan (150 µgmL⁻¹) on G5 amine-terminated dendrimer-mediated complement activation in plasma of two healthy individuals (M26 and F33) and a plasma from a subject with MBL deficiency (M48) on reconstitution with MBL-MASPs (denoted as M48*) (equivalent to 3 µg MBL mL⁻¹). e G5 amine-terminated PAMAM dendrimer-mediated complement activation in a commercially obtained C2-depleted human serum is restored on C2 (30 µgmL⁻¹) addition. f C3-dependent complement activation by G5 amine-terminated PAMAM dendrimers as a measure of C3a-desArg. g C3-dependent complement activation by G5 amine-terminated PAMAM dendrimers as a measure of sC5b-9. In f and g, compstatin concentration was 40 µM. h G5 amine-terminated PAMAM dendrimers promote alternative pathway turnover (as a measure of Bb rises over background) through the amplification loop. In all panels, the dendrimer concentration is 0.132 mM. In all panels, bars show mean values ± s.d. of three separate experiments, and each dot indicates the mean of three technical replicates. In f and g, each black rhombus dots in open columns represent the mean of three technical replicates of plasma background levels of C3a-desArg and sC5b-9, respectively. All p values (unpaired, two-sided) are compared with their respective controls. Source data are available in Source data file.