Urinary immunoglobulins in the adult pig.

Immunoglobulins IgG and IgA occur in adult sow urine as intact molecules, but not immunoglobulin IgM. Molecular fragments of all these types do however occur, although fragments of IgA are not as easily detectable as those of IgG. Urinary IgA was isolated and shown to exist primarily as a dimer. Antigenically and electrophoretically it is similar to the secretory IgA molecules of colostrum, milk, saliva and intestinal juice, and like those molecules possesses secretory component. Urine IgG is present as a 7S molecule and is similar to serum IgG. The IgG:IgA ratio of intact molecules in adult sow urine was 6:1; a similar ratio is found in colostrum. This compares with a 10:1 ratio occurring in serum. Thus there is relatively more IgA in urine than in serum compared to IgG, but relatively less than in milk.