What is the function of IgA antibody?
Immunoglobulin A (IgA) is the most abundant type of antibody in the body, comprising most of the immunoglobulin in secretions and a significant amount of circulating immunoglobulin. In secretions, it serves to protect the mucosal tissues from microbial invasion and maintain immune homeostasis with the microbiota.
Is IgA a dimer or monomer?
IgA in serum is mainly monomeric, but in secretions, such as saliva, tears, colostrums, mucus, sweat, and gastric fluid, IgA is found as a dimer connected by a joining peptide. Most IgA is present in secreted form.
Where is IgA secreted?
IgA subclasses differ in distribution and function. IgA1 is present mainly in the serum (it accounts for 85 per cent of serum IgA) and predominates in secretion in the upper intestine and in the various mucosal glands. IgA2 predominates in secretion in the large intestine and in the female genital tract.
What is the difference between IgA and secretory IgA?
Whereas secretory IgA is dimeric, serum IgA is composed mainly of monomers. The monomeric form and the lack of the secretory component enable serum IgA to bind to Fcα-receptor I (FcαRI) expressed by myeloid cells, such as monocytes, neutrophils, and some subsets of macrophages and dendritic cells (DCs)3.
Is IgM a dimer?
To obtain a better understanding of the elusive structure of the IgM Fc, we first characterized the isolated Fc domains. The Cμ2 domain, the most N-terminal domain of the IgM Fc, replaces the hinge region found in IgG (25). It forms a disulfide-linked dimer with a unique interface dominated by hydrophobic interactions.
Is IgE a dimer?
We conclude that IgE that has been crosslinked to form dimers prior to the addition to mast cells can serve as a unit signal for triggering IgE-mediated exocytosis.
Why is secretory IgA important?
Secretory IgA (SIgA) plays an important role in the protection and homeostatic regulation of intestinal, respiratory, and urogenital mucosal epithelia separating the outside environment from the inside of the body.
What does it mean if your secretory IgA is low?
Low SIgA levels generally have an increased risk of food sensitivities, inflammatory bowel disease (IBD), Irritable Bowel Syndrome (IBS), intestinal permeability, autoimmunity, coeliac disease and gastrointestinal infections.