Enterohepatic circulation of IgA does not occur in rats

The concentration of IgA in rat bile falls with time after cannulation. This effect is particularly marked in germ-free animals, in which the initial level of IgA is markedly subnormal anyway. The fall suggests that the cannula is draining to the exterior IgA, which would normally be recirculated. However, when germ-free or normal rats were supplied intraduodenally with bile whose IgA carried 125I, no transfer of this labelled IgA from the gut lumen back to the bile could be detected.