<prompt> In respiratory and GIT infections, which is the most affected immunoglobulin?IgAIgGIgMIgD  <response>: Ans. is a i.e., IgARef: Ananthanarayan,9the, p. 97 - 98 and 8the, p. 98 - 99 IgA Secretory IgA is selectively concentrated in secretions and on mucous surfaces forming an antibody paste and is believed to play, an important role in local immunity against respiratory and intestinal pathogens. 