The title of this special topic invites us to identify areas in the field of IgA biology that are uncertain or in need of clarification. The inductive phase of the human intestinal IgA response has been a controversial area for some years. Therefore, to structure this review, we have identified key questions that are debated in this field. We have provided explanations of the origins of the uncertainties and have provided our own reasoned answers to the questions we pose.
Keywords: IgA; gut-associated lymphoid tissue; human.