C5AR1 and Alzheimer disease: In addition to the potential for greater access to the brain, an advantage of a selective C5aR1 antagonist vs Eculizumab for long term treatment of diseases such as AD is that, while it blocks effects of C5a, the generation of C5b by the uninhibited cleavage of C5 is still able to initiate the assembly of the bacteriolytic C5b-9 complex upon complement activation by pathogens.