C5b8

C5b8 refers to a complex formed as part of the complement system, a critical component of innate immunity. Specifically, it is a sub-lytic or intermediate membrane attack complex (MAC) that can form on target cell surfaces. The complement cascade, a series of enzymatic reactions, can be initiated by various triggers. Following a series of cleavages and assemble, the C5b, C6, C7, and C8 proteins come together. C5b8 then inserts into the lipid bilayer of a cell membrane. This initial insertion can create a small pore. In the presence of sufficient C9 molecules, the full lytic MAC (C5b-9) can form, leading to cell lysis. However, C5b8 itself can exist and exert biological effects without necessarily progressing to full pore formation and lysis. Its formation is an essential step in the generation of the membrane attack complex and plays a role in the elimination of pathogens and damaged host cells. The precise function and regulation of C5b8 are areas of ongoing research within immunology.