Molecular Classification
Serine Protease, Complement Component, Enzyme
Other Names
Factor Bb, CFB fragment Bb
Disease Roles
Autoimmune disordersChronic renal failureInflammation

Complement Factor Bb Overview

Complement factor Bb is a serine protease fragment derived from complement factor B. It is a key component of the alternative pathway C3 and C5 convertases, playing a central role in amplifying the complement cascade and mediating immune responses. Bb is generated upon cleavage of factor B by factor D when factor B is bound to C3b. As a catalytic subunit, Bb is essential for cleaving C3 and C5, leading to opsonization, inflammation, and cell lysis. Elevated levels of Bb can serve as a biomarker for diseases involving dysregulated complement activity.

Mechanism of Action

Bb is a catalytic subunit of the C3 and C5 convertases, which cleave C3 and C5, respectively, leading to downstream complement activation. Therapeutic strategies may aim to inhibit its activity or formation to dampen excessive complement activation.

Biological Functions

Complement activation
Immune response amplification
C3 convertase formation
C5 convertase formation
B lymphocyte proliferation and differentiation
Monocyte spreading
Lymphocyte blastogenesis
Immunosuppression
Apoptosis regulation
Erythrocyte lysis

Disease Associations

Autoimmune disorders
Chronic renal failure
Inflammation
Infection

Safety Considerations

  • Inhibition of Bb could lead to immunosuppression and increased susceptibility to infection.
  • Uncontrolled complement activation can lead to inflammatory damage.

Associated Biomarkers

Biomarker
Elevated plasma levels of Bb indicate increased alternative pathway activation.