Creative Biolabs provides customized non-IgG antibody services, from non-IgG antibody production to non-IgG research innovation. With years of experience, our scientists can provide high-quality IgA antibody products and services to precisely meet your needs.
Introduction of IgA
In most organisms, IgA exists in the circulation as a polymer. IgA is the most important antibody class in mucosal sites and the second popular antibody class in human serum. IgA has always been defined as a non-inflammatory antibody. This is true for secreted IgA (SIgA), which acts as the first line of defense in the mucosal area by inhibiting the adhesion of microorganisms. In addition, SIgA also plays an important role in the removal of immune complexes and the neutralization of intracellular viruses. However, it is worth noting that serum IgA can trigger inflammation after binding to the IgA Fc receptor I (FcαRI).
Role of IgA and IgA Receptors in Immunity
IgA and IgA receptors are closely related to mucosal and systemic immunity. IgA-related diseases are usually accompanied by elevated serum IgA levels and IgA tissue deposition. These diseases include IgA nephropathy, ankylosing spondylitis, HIV infection, alcoholic cirrhosis, and herpetiform dermatitis. On the other hand, IgA receptor deficiencies have a serious impact on immune hemostasis and may cause various adverse reactions such as allergies, intestinal autoimmunity, and vasculitis.
Functions of Common IgA Receptors
IgA can interact with receptors on a variety of cells, including polymeric immunoglobulin receptor (pIgR), Fc receptor-like 4 (FcRL4), asialoglycoprotein receptor (ASGPR) and FcaRI. PIgR can mediate the transport of dimeric IgA to the mucosal cavity, where it is released in the form of SIgA. What's more, B cells display inhibitory IgA receptor FcRL4, which is thought to help modulate mucosal IgA responses. ASGPR is expressed in the liver, which is involved in the clearance of IgA. Finally, it is worth noting that the IgA Fc receptor FcαRI is expressed by bone marrow cells. It has been shown that the interaction between monomeric serum IgA and FcαRI induces inhibitory signals. In contrast, the close combination of IgA immune complex and FcαRI induces an inflammatory response, which provides new possibilities for solving infections. However, studies have shown that excessive IgA immune complexes can activate immune cells, leading to autoimmune diseases. In summary, the number of different IgA receptors, their differential expression on cells, and the effector functions induced by different IgA are involved in maintaining homeostasis.
Fig.1 Interaction of FcαRI with IgA. (Breedveld, 2019)
Classical IgA Receptors
- IgA-pIgR Interaction
- IgA-Fcα/μR Interaction
- Transferrin Receptor
- Asialoglycoprotein Receptor
- DC-SIGN Receptor
- Fc Receptor-like Proteins
- Other Functional Receptors
- IgA and the Intestinal Microbiota
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- Breedveld, A.; Van Egmond, M. IgA and FcαRI: pathological roles and therapeutic opportunities. Frontiers in immunology. 2019, 10: 553.
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