IgA in Blood and Thoracic Duct Lymph: Concentration and Degree of Polymerization

Abstract

Lymph fluid and serum samples from 4 mammalian species were studied for the concentration and degree of polymerization of Ig[immunoglobulin]A. In the mouse, rat and dog, circulating IgA probably represents only a small fraction of all IgA entering the blood stream from the lymph vessels. A majority of the input IgA of oligomeric type (13S, 11S and 9S) in these species is cleared rapidly. Monomeric IgA, and in the mouse and the dog the dimeric (9S) variety, dwell much longer in the blood, and because of this they form the majority of the circulating IgA. The blood concentration of IgA is high in man, a species whose blood seems to receive mostly monomeric IgA. It is much lower in the rat, mouse and dog, and in these species most of IgA entering the blood is probably oligomeric.