This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anitibody, Subject name: Microbiology
Major immunoglobulin secreted by intestine - 
Select and explain. 
A. IgG, B. IgM, C. IgA, D. IgD
C: IgA
Answer: C: IgA 
Explanation: Ans. is 'c' i.e., IgA IgAo It is the second most abundant antibody (after IgG).o It is major immunoglobulin in dost rum, saliva, tears, respiratory and gastrointestinal secretions. Ig A occurs in two forms.o Slg 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,.IgA1-predominant serum IgAIgA2-predominant secretory IgA