IMMUNOLOGY

Detailed explanation-1: -IgA is the major antibody in secretions found in saliva, tears, colostrum, intestinal, genital tract, and respiratory secretions.

Detailed explanation-2: -Immunoglobulin A (IgA): It’s found in the linings of the respiratory tract and digestive system, as well as in saliva (spit), tears, and breast milk.

Detailed explanation-3: -The two principal antibody classes present in saliva are secretory IgA (SIgA) and IgG; the former is produced as dimeric IgA by local plasma cells (PCs) in the stroma of salivary glands and is transported through secretory epithelia by the polymeric Ig receptor (pIgR), also named membrane secretory component (SC).

Detailed explanation-4: -Although all three major classes of immunoglobulins are present in human colostrum and milk, only IgA and IgM are locally produced in the human mammary gland. These immunoglobulins protect neonates and infants against infection, particularly IgA protects against respiratory tract and gastrointestinal infections.

Detailed explanation-5: -Two major antibody classes operate in saliva: secretory IgA (SIgA) and IgG. The former is synthesized as dimeric IgA by plasma cells (PCs) in salivary glands and is exported by the polymeric Ig receptor (pIgR). Most IgG in saliva is derived from serum (mainly via gingival crevices), although some is locally produced.