Figure 9.

Basolateral dIgA stimulates apical transport of pIgR–dIgA complexes formed only at the basolateral surface. (A and B) Modifications made to the protocol presented in Figure 1 and described in the text. In this experiment we followed the apical transport of a pool of pIgR biotinylated and endocytosed into the PMC from the apical surface. (C) Quantitations of the apical transport of pIgR in the presence of dIgA, medium alone added apically at stage B, or dIgA added both apically at stage B and basolaterally at stage E. n = 3; p > 0.5 for +Apical dIgA and +Apical dIgA/+dIgA stage E.