Related Experiment Videos
Complement factors H and I synthesized by B cell lines function to generate a growth factor activity from C3
V Vĕtvicka1, W Reed, M L Hoover
1Department of Microbiology and Immunology, University of Louisville, KY 40292.
Journal of Immunology (Baltimore, Md. : 1950)
|May 1, 1993
Summary
B lymphocytes use endogenous factors H and I to convert complement C3 into a CR2 ligand, promoting cell growth. This study elucidates a novel mechanism for B cell proliferation dependent on complement system interactions.
Area of Science:
- Immunology
- Complement System Biology
Background:
- B lymphocytes express CR2 (CD21), a receptor for C3 fragments.
- Previous studies showed Raji B cells grow with transferrin and CR2 ligands, but native C3's role was unclear.
Purpose of the Study:
- To investigate how native C3 acts as a growth factor for B cells, specifically Raji cells.
- To determine if Raji cells utilize endogenous factors H and I to generate a CR2 ligand from C3.
Main Methods:
- Polymerase Chain Reaction (PCR) to detect factor I mRNA in Raji cells.
- Monoclonal Antibody (mAb) ELISA to confirm secretion of Raji cell factor I.
- Culturing various B and T cell lines with transferrin and C3 to assess growth dependency.
Main Results:
- Raji cells synthesize and secrete functional factor I.
- Raji cells require C3 and transferrin for growth, unlike other cell lines tested.
- Anti-factor H and anti-factor I mAbs inhibited C3-dependent Raji cell growth.
Conclusions:
- Raji cells convert native C3 to a CR2-binding growth factor using endogenous factors H and I.
- This mechanism highlights a novel role for the complement system in B lymphocyte proliferation.