• Species Reactivity

  Human

• Specificity

  Detects human FCAR/CD89 in direct ELISAs. In direct ELISAs, no cross-reactivity with Fc gamma RIA, RIIA, or RIIIB is observed.

• Source

  Monoclonal Mouse IgG1 Clone # 488032

• Immunogen

  NS0 mouse myeloma cell line transfected with human FCAR/CD89    
  Gln22-Lys287    
  Accession # P24071

• Formulation

  Supplied 0.2 mg/mL in a saline solution containing BSA and Sodium Azide.

• Label

  Alexa Fluor 750

Applications

• Recommended    
  Concentration

  Sample

• Flow Cytometry

  0.25-1 µg/10    ⁶ cells

  Human blood‑derived granulocytes

• 
  

Please Note: Optimal dilutions should be determined by each laboratory for each application.  are available in the Technical Information section on our website.

Preparation and Storage

• Shipping

  The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.

• Stability & Storage

  Store the unopened product at 2 - 8 °C. Do not use past expiration date.

Background: FCAR/CD89

FCAR, also called Fc alpha RI or CD89, is a variably glycosylated 50‑100 kDa myeloid-specific type I transmembrane (TM) Fc receptor for IgA that is a member of the multichain immune recognition receptor (MIRR) family (1‑3). Human FCAR contains a 21 amino acid (aa) signal sequence and extracellular (ECD), TM and cytoplasmic domains of 206, 19 and 41 aa, respectively (4). Arg230 within the TM domain supports interaction with the ITAM-containing signaling subunit, FcR gamma, which contains a TM Asp (5‑7). Two ECD C2-type Ig-like domains (EC1 and 2) are oriented at right angles (8). Up to two molecules of FCAR can bind one molecule of serum IgA via EC1 (8). Many splice variants have been reported, but only two have been identified as proteins (9, 10). The a.2 form, which lacks 22 aa just prior to the TM domain, is exclusively expressed in alveolar macrophages. The a.3 form lacks EC2. FCAR binds monomeric, polymeric and secretory IgA, but does not mediate the barrier function of secretory IgA in mucosal epithelium (1‑3). Shedding and circulation of polymeric IgA/FCAR immune complexes has been reported (11). Circulating neutrophils, eosinophils, and monocytes express FCAR (12). Tissue expression of FCAR is mainly from neutrophils; FCAR is downregulated as monocytes differentiate to tissue macrophages (12). On neutrophils, a significant amount of FCAR lacks FcR gamma, but can still be endocytosed to early endosomes and recycled to the cell surface (5). Binding of serum IgA to FCAR is transient and anti-inflammatory, inhibiting IgG or IgE-induced degranulation (6). Sustained aggregation of FCAR results in inflammatory responses (6). FcR gamma signaling is required for these and for transport to late endosomes (5‑7). Human FCAR shows 55‑58% aa identity with rat, horse and cow FCAR. No ortholog occurs in mouse. FCAR structure resembles the KIR/ILT/LIR/MIR family more than other IgA receptors, including pIgR, Fc alpha /μR, asialoglycoprotein receptor (ASGR1) and transferrin receptor (TfR) (1‑3).

• References:

1. Wines, B. D. and P. M. Hogarth (2006) Tissue Antigens 68:103.

2. Otten, M. A. and M. van Egmon (2004) Immunol. Lett. 92:23.

3. Montiero, R. C. and J. G. J. van de Winkel (2003) Annu. Rev. Immunol. 21:177.

4. Maliszewski, C. R. et al. (1990) J. Exp. Med. 172:1665.

5. Launay, P. et al. (1999) J. Biol. Chem. 274:7216.

6. Pasquier, B. et al. (2005) Immunity 22:31.

7. Shen, L. et al. (2001) Blood 97:205.

8. Herr, Y. et al. (2003) Nature 423:614.

9. Patry, C. et al. (1996) J. Immunol. 156:4442.

10. Togo, S. et al. (2003) FEBS Lett. 535:205.

11. van der Boog, P. J. M. et al. (2002) J. Immunol. 168:1252.

12. Hamre, R. et al. (2003) Scand. J. Immunol. 57:506.

• Long Name:

  IgA Fc Receptor

• Entrez Gene IDs:

  2204 (Human); 365183 (Rat); 102145896 (Cynomolgus Monkey)

• Alternate Names:

  CD89 antigen; CD89; CD89IgA Fc receptor; Fc alpha receptor; Fc fragment of IgA, receptor for; FCAR; immunoglobulin alpha Fc receptor