Table 1.

Outstanding questions in human IgA immunobiology.

Question	Authors’ best guess answer	Degree of certainty in answer (%)
Do the events that initiate the human IgA response, occur exclusively in gut-associated lymphoid tissue?	Yes	90
Is there an equivalent of murine cryptopatch precursor of ILFs in humans?	No	95
Can gut-associated lymphoid tissue be acquired in response to bacterial antigens in humans?	Yes	100
Are there T cell dependent and T cell independent routes to IgA production in man?	Yes	95
Are intestinal T cell dependent IgA responses, necessarily dependent on conventional cognate interactions in humans?	No	60
Do innate receptors have any role in driving the human mucosal IgA response?	Yes	100
Might germinal centers be involved in both T cell dependent and T cell independent IgA responses in humans?	Yes	95
Are there differences in the induction of IgA responses that seed the small bowel and the colon?	Yes	70
Is the human intestinal IgA response antigen specific?	Yes	100
Is light chain drifting a feature of the IgA response?	Yes	100
Is there local proliferation of plasma cell precursors in the human intestinal lamina propria?	No	90
Are human intestinal IgA plasma cells long lived?	Yes	90