Description:
<jats:title>Abstract</jats:title>
<jats:p>Mouse factor B was purified and a monospecific anti-serum was raised. The physicochemical data of this protein (108,000 m.w., 5.9 S, 5.9 to 6.05 isoelectric point) were determined. The functional behavior resembles that of human and guinea pig factor B and it operates efficiently in the C3 feedback cycle of the alternative pathway of complement activation. A provisional scheme is given for the operation of the C3bB̄ enzyme on the cellular (macrophage) level.</jats:p>