Human Fcα Receptor (FCAR): Structure, Function, and Roles in Immune Defense

1. Concept

The human Fcα receptor (FCAR, also known as CD89) is a type I transmembrane glycoprotein that specifically binds to the Fc region of IgA antibodies. Expressed on neutrophils, monocytes, macrophages, and eosinophils, FCAR serves as a critical bridge between mucosal humoral immunity and cellular effector functions, mediating phagocytosis, ADCC, inflammatory mediator release, and immune regulation.

2. Research Frontier

FCAR has emerged as a key regulator in mucosal immunity, infection control, chronic inflammation, and tumor surveillance. As IgA is the most abundant antibody at mucosal surfaces, understanding FCAR‑mediated signaling is essential for developing next‑generation IgA‑based therapeutics, vaccines, and immunomodulatory agents.

3. Research Significance

FCAR is central to frontline antimicrobial defense and immune homeostasis:

• Initiates clearance of IgA‑opsonized pathogens
• Regulates balanced inflammatory responses
• Contributes to antiviral and antitumor immunity
• Serves as a potential target for treating infection, autoimmunity, and cancer
• Supports innovation in IgA antibody drug development

4. Core Mechanisms and Biological Functions

4.1 Structural Features

• Molecular weight: 50–100 kDa (glycosylation‑dependent)
• Extracellular domain: two C2‑type Ig‑like domains for IgA Fc binding
• Transmembrane and cytoplasmic domains for signaling
• Glycosylation variants modulate affinity and cell‑specific function

4.2 Key Effector Functions

1. Phagocytosis

Activates neutrophils and macrophages to engulf IgA‑coated pathogens.

2. Antibody‑Dependent Cell‑Mediated Cytotoxicity (ADCC)

Kills virus‑infected or tumor cells via IgA‑targeted cellular cytotoxicity.

3. Inflammatory Mediator Release

Induces secretion of TNF‑α, IL‑1β, IL‑6, and chemokines to amplify local immunity.

4. Immune Homeostasis

Modulates immune cell activation to prevent excessive inflammation.

4.3 Roles in Health and Disease

• Infectious Diseases: Defends mucosal surfaces against bacteria and viruses (e.g., influenza, Streptococcus pneumoniae).
• Autoimmune Diseases: Dysregulation linked to rheumatoid arthritis and intestinal inflammatory disorders.
• Tumor Immunology: Mediates antitumor activity in mucosa‑associated cancers; targeted for next‑generation immunotherapies.

4.4 Future Research Directions

• High‑resolution structural analysis of FCAR‑IgA complexes
• Cell‑specific FCAR regulatory mechanisms
• Development of FCAR‑targeted therapies and IgA‑based drugs
• Biomarker and therapeutic applications in inflammation and cancer

5. ANT BIO PTE. LTD. Product Empowerment

High‑quality FCAR proteins are essential for binding assays, drug screening, antibody development, and mechanistic studies. ANT BIO PTE. LTD. provides reliable recombinant FCAR reagents via its UA sub‑brand.

Featured Recombinant Protein

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How This Product Empowers Research

• Enables IgA‑FCAR binding kinetics and affinity assays
• Supports screening of IgA‑based therapeutic antibodies
• Facilitates functional characterization and inhibitor development
• Ideal for flow cytometry, ELISA, SPR, and structural biology

6. Brand Mission

ANT BIO PTE. LTD. is a leading provider of premium life science reagents, focusing on high‑quality antibodies, recombinant proteins, assay kits, and general laboratory reagents. We operate three specialized subbrands to cover full research workflows:

• Absin: General reagents, buffers, and ELISA kits
• Starter: High‑performance antibodies and functional magnetic beads
• UA: Recombinant proteins for research, immunization, and validation

We are committed to delivering stable, reliable, and traceable reagents to accelerate breakthroughs in tumor immunology, oncology drug development, and translational medicine.

7. Related Product List

• FCAR / CD89 His‑tag recombinant protein (UA020007)
• IgA Fc region proteins and standards (UA)
• FCAR‑specific antibodies (Starter)
• Immune cell function ELISA kits (Absin)
• Protein purification and buffer systems (Absin)

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ANT BIO PTE. LTD. – Empowering Scientific Breakthroughs

At ANTBIO, we are committed to advancing life science research through high-quality, reliable reagents and comprehensive solutions. Our specialized sub-brands (Absin, Starter, UA) cover a full spectrum of research needs, from general reagents and kits to antibodies and recombinant proteins. With a focus on innovation, quality, and customer-centricity, we strive to be your trusted partner in unlocking scientific mysteries and driving medical progress. Explore our product portfolio today and elevate your research to new heights