Human Complement Factor B, CFB ELI

Factor B which is part of the alternate pathway of the complement system is cleaved by factor D into 2 fragments: Ba and Bb.

Bb, a serine protease, then combines with complement factor 3b to generate the C3 or C5 convertase.

It has also been implicated in proliferation and differentiation of preactivated B-lymphocytes, rapid spreading of peripheral blood monocytes, stimulation of lymphocyte blastogenesis and lysis of erythrocytes.

Ba inhibits the proliferation of preactivated B-lymphocytes.