IMMUNOLOGY

Detailed explanation-1: -IgA has the capacity to form dimers, in which two monomer units, each comprising two heavy chains and light chains, are arranged in an end-to-end configuration stabilized by disulphide bridges and incorporation of J (joining) chain.

Detailed explanation-2: -While IgA is known to play a common role in protection at mucosal surfaces [7], the levels, forms, and distribution of IgA vary. For example, in species commonly used in experimental research, including mice, rats, and rabbits, the main form of IgA in serum is dimeric rather than the monomeric form seen in humans.

Detailed explanation-3: -Secretory (S) Immunoglobin (Ig) A is the predominant, mammalian mucosal antibody; it is a polymeric antibody assembled in plasma cells that link two IgA monomers and a single copy of the joining chain (JC) to form dimeric (d) IgA (and to a lesser extent, higher order polymers) (Woof and Russell, 2011).

Detailed explanation-4: -Serum IgA molecules are mostly monomeric, while secretory IgA molecules are found as dimers and, to a lesser extent, as trimers and tetramers. In the dimer, two IgA molecules are linked together by another polypeptide designated as J-chain.