Age-dependent loss of dimeric immunoglobulin A receptors in the liver of the Fischer 344 rat.

Characterization of the receptor for dimeric immunoglobulin A (dIgA) on an isolated rat liver plasma membrane-enriched fraction showed a single class of binding sites specific for dIgA. Both the rat and human immunoglobulins competed for the binding site, but human IgA bound much less strongly to the receptor. Other proteins did not compete for the dIgA receptor, including asialoorosomucoid. Scatchard analysis of binding data from young adult, mature, and senescent animals indicated an age-dependent decrease in the number of receptors present on liver plasma membranes. This loss of receptors with increasing animal age may be responsible for the concomitant reduction in hepatobiliary secretion of dIgA.