Figure 5.

Recombinant renin does not induce complement activation.

a) Renin does not increase complement activity in the fluid phase. Recombinant FLAG-tagged renin (batch F) was spiked in at >1000x higher than the concentration observed in patients. Three examples are shown – patient #6 with negative pre-spiking fluid-phase activity [no C3 activation products (C3AP) shown in the second lane] and no increase with spiking (third lane); patients #7 and #8 with positive pre-spiking fluid-phase activity (second lane) and no increase with renin spiking (third lane) (total 15 patients tested; D = EDTA, complement activity stopped; G = EGTA, supplemented with MgCl₂ making AP activation possible); b) Increased renin concentration does not increase complement deposition on cell surfaces. C3b deposition does not increase as renin concentration is increased in both pooled normal human serum (top) and patient serum (bottom). As a positive control, FD (instead of renin) was spiked in at a final concentration of 10 μg/ml (~10x above normal) (right). Renin low = final concentration 1.9 nM or ~19x above the highest renin observed in patient. Renin high = final concentration 19 nM or ~190x above the highest renin observed in patients. FD added to a final concentration of 10 ug/ml (~10x higher than controls) (blue = nuclei, DAPI; green = C3b; bar = 200 μm).