RCR2 Antibody

Target and Biological Role of CR2/CD21

CR2 (CD21) is a transmembrane glycoprotein that binds complement fragments (e.g., C3d) and enhances B cell responses to antigens . Its functions include:

• Antigen Presentation: Facilitates B cell recognition of antigen-C3d complexes.

• Immune Regulation: Modulates antibody production and B cell tolerance .

• Pathogen Defense: Mediates host responses to pathogens by linking innate and adaptive immunity .

RCR2 antibodies specifically target epitopes on CR2, enabling researchers to manipulate or detect CR2 activity in experimental models.

3.1. Immune Response Modulation

• Adult vs. Neonatal B Cells: Anti-CR2 antibodies enhance PS4-specific antibody responses in adult B cells but require higher concentrations to activate neonatal B cells .

• Synergy with 8MGuo: Combining anti-CR2 antibodies with 8-mercaptoguanosine restores neonatal B cell responsiveness to TI-2 antigens .

3.2. Imaging Activated Complement

• Technetium-99m Labeling: Site-specific radiolabeling of rCR2 (via His-tag) yields stable conjugates (>95% radiochemical purity) for detecting C3d deposits in preclinical models .

• Specificity: Radiolabeled rCR2 binds C3d⁺ red blood cells, while mutants (e.g., K41E CR2) or irrelevant proteins (e.g., C2A) show no binding .

3.3. Therapeutic Potential

• Transplant Rejection: CR2 deficiency (Cr2^−/−) in GalT^−/− mice reduces anti-αGal IgM production, suggesting CR2’s role in antibody-mediated rejection .

Key Research Insights

• CR2-C3d Binding: Surface plasmon resonance confirms rCR2 binds C3d with nanomolar affinity, critical for imaging applications .

• Neonatal Immunity: Low CR2 expression correlates with neonatal B cell unresponsiveness to TI-2 antigens, reversible via CR2 stimulation .

• Preclinical Imaging: rCR2-Tc^99m demonstrates specificity for C3d in ischemia-reperfusion injury models, highlighting diagnostic potential .