Characterization of Antibodies in Human Urine*

Human urine contains proteins that have been demonstrated to be antigenically identical with se-rum immunoglobulins (1-8). The immunoglobu-lins usually present in urine have been 7 S-y-globu-lin and 382A-globulin (3,7), whereas /82M-globulin has been found in only a few cases (9). A low molecular weight protein, antigenically related to 7 S y-globulin, has also been observed (2, 4-8). This low molecular weight y-globulin ('yL) 1 has been reported to be identical to the light (L) poly-peptide chains that form part of the 7 S y-globulin molecule, and it has been suggested that they were free L chains representing the normal counterparts to Bence Jones proteins (10-12). Antibody activity in urine has been demon-strated against several microorganisms. Agglu-tinins reacting with Vibrio cholera and Salmonella typhi (13) and precipitins against diphtheria and tetanus toxoid (14), as well as neutralizing activity against polio virus (15), have been described. Usually, the antibodies responsible for these ac-tivities have not been further characterized im-munologically or physicochemically. The reports of Remington, Merler, and their colleagues (16, 17), however, present evidence that precipitating activity against tetanus toxoid and neturalizing activity against polio virus reside in a protein frac-tion of a molecular weight of 12,900. These au-thors found no antibody activity in material that