Figure 7.

(a) Classical pathway complement activity of human serum incubated in presence of predator and/or prey as measured by percent haemolysis of sensitised erythrocytes. Human serum was incubated at 37 °C alone as a control (Serum alone) or in the presence of K. pneumoniae (Serum + Kp), in the presence of B. bacteriovorus HD100 (Serum + HD100) or in the presence of both K. pneumoniae and B. bacteriovorus HD100 (Serum + Kp + HD100). Serum was periodically sampled, filtered (0.2 µM) and diluted to 25% prior to measuring serum complement activity as determined by percent haemolysis of erythrocytes. CH₅₀ serum values were calculated from these data and these are included in supplementary materials, Supplementary Table S1. (b) Enumeration of live bacterial populations incubated in human serum used for determining classical pathway complement activity. Predator and prey numbers in human serum were determined immediately prior to filtering (0.2 µM) and filtered aliquots were subsequently used for determining complement activity (panel a).