Which of the following statements are correct regarding immunoglobulin A.
(A). IgA is the main class of antibody in secretions such as tears, saliva.
(B). IgA is also found in secretions of lungs and intestine.
(C). IgA is the first line of defense against infection at these sites.
(D). IgA is the main immunoglobin in the bloodstream late in the primary immune response.
Choose the correct answer from the options given below:
1
(A), (B) and (D) only.
2
(A), (B) and (C) only.
3
(A), (B), (C) and (D).
4
(B), (C) and (D) only.