Secretory gamma-A in normal urine.

The physicochemical nature of gammaA was investigated in normal male and female urine concentrated approximately 1000 times. Sucrose density gradient ultracentrifugation and Sephadex G-200 chromatography revealed that urinary gammaA has sedimentation properties intermediate between 19S and 7S molecules. Isolation of urinary gammaA by DE 52 chromatography free of other immunoglobulins with subsequent antigenic analysis showed that the urinary gammaA-molecule is antigenically indistinguishable from the gammaA-molecules found in other external secretions and has a corrected sedimentation coefficient of 11.8S. In addition, like other secretory gammaA-molecules and unlike serum polymeric gammaA, urinary gammaA resisted mild reductive measures with 0.1M beta-mercaptoethanol. Free or unattached secretory "piece" was found in all normal urines tested and in agammaglobulinemic urine. Secretory "piece" antigenic determinants were also found in ureteric urine. The average daily excretion of urinary gammaA was 1.1 mg. The maximum excretion of urinary 7S gammaG per 24 hr was approximately 3 mg.