Development of a radioimmunoassay for a high molecular mass tubular antigen in urine--its application for early detection of tubular damage.

In order to isolate urinary kidney antigens, the gammaglobulins fraction of an antiserum against human kidney cortex plasma membranes was coupled to Sepharose 4B. By immunospecific affinity chromatography an antigen fraction was obtained from the urine of a patient suffering from severe kidney disease. After gel filtration, the main fraction, eluted with the exclusion volume of a Sephadex G-200 column and enriched 16 000-fold, was labelled with 131I and used in a radioimmunoassay system.

Change in alkaline phosphatase isoenzyme pattern in urine as possible marker for renal disease.

The human kidney contains two types of alkaline phosphatase (AP) isoenzymes: a hepatic type of AP and an intestinal-like AP. Intestinal-like AP, measured by immunotitration techniques, is a minor component (1 to 4%) of the total AP activity. It is found only in the particle-free fraction (cytoplasm) and is located, with immunofluorescent techniques, in some of the proximal convoluted tubules.