Immunoglobulin present in mouth local secretion s-

Ans. is 'a' i.e., IgA IgAo It is the second most abundant antibody (after IgG).o It is major immunoglobulin in clostrum, saliva, tears, respiratory and gastrointestinal secretions. Ig A occurs in two forms.IgASerum IgASecretory IgA (SIgA)o Monomero Dimero Found in serumo Two monomer units are joined together by a glycopeptide - Jchain o Contains glycine rich polypeptide secretory component, which protectsIgA from denaturation by bacterial proteases.o SIg A and J chain are synthesized by plasma cells.o Secretory component is produced by mucosal or glandular epithelial cells.o Two subclasses of IgA have been described Ig A| & Ig A?.IgAI - Predominant serum Ig AIg A2 - Predominant secretory Ig A