Renal tubular antigen excretion in normal human urine. I. Immunochemical indentification

The modified vaccination technique designed to prevent and cure acute and chronic disorders

In spite of enormous efforts there have been no solutions to date for preventing/terminating certain acute and chronic disorders of humans by vaccination or drugs. Yet it is well understood that if the target antigen (ag) could be presented appropriately to the cells of the immune system then solutions could be found. Recently, the Barabas research group has introduced and described the third vaccination method - called modified vaccination technique (MVT) - which has the ability to provide a corrective immune response in experimental animals with an autoimmune kidney disease. Injections of immune complexes - made up of the target ag and specific non-pathogenic IgM antibodies directed against the target ag - achieved downregulation of pathogenic immune responses and tolerance to self was regained. Utilizing the immune system's natural abilities to respond to corrective information, the MVT technique was able to prevent an autoimmune kidney disease from occurring (prophylactic effect) in experimental animals, and when present, terminating it (therapeutic effect) specifically and without measurable side effects.It is predicted that the application of the MVT will have the potential in the future to revolutionize the preventative and therapeutic options for dealing with chronic disorders in humans (such as autoimmune disease, cancer and acute chronic infections) and achieve cures.

Antigen-specific down-regulation of immunopathological events in an experimental autoimmune kidney disease

Heymann nephritis (HN) is an experimental autoimmune disease of rats characterized by immune-complex (IC) depositions on the epithelial side of the glomerular basement membrane (GBM) and by proteinuria. Several forms of HN have been produced by various investigators, but one thing has been common to all of them, namely their inducement by the development of pathogenic IgG autoantibodies (aabs). The aim of this review is to describe how pathogenic IgG aab production (which initiates and maintains the disease) in slowly progressive HN (SPHN) can be specifically terminated by injections of ICs made up of native rat renal tubular antigens and IgM antibodies directed against them.

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. Soluble kidney antigens, presumably of proximal tubular origin, could be detected and quantified by the assay system in urine samples of patients with various diseases. The samples did not need to be treated, either concentrated or dialyzed, before application. The results of our experiments show a correlation between antigen excretion and kidney damage. Rejection episodes in patients with kidney transplants could be recognized early by enhanced antigen excretion. Potentially nephrotoxic drugs caused antigen excretion as well. In normal, healthy subjects output of the antigen was very low. The assay system might be of value for monitoring renal diseases.

Radioimmunoassay for urinary renal tubular antigen: a potential marker of tubular injury

A human proximal renal tubular epithelial antigen (designated HRTE-1) was isolated and purified from a crude tubular preparation (Fx1A) by a process of salt fractionation, DEAE anion-exchange chromatography, and Sephadex G-200 gel filtration. Utilizing 125I-HRTE-1 and a rabbit antiserum specific for the proximal tubular brush border, as determined by immunofluorescent microscopy, a radioimmunoassay by competitive protein-binding was developed. HRTE-1 was demonstrated in serum and urine and in extracts of a variety of body organs. A range of concentrations for normal random urine samples and 24-hr urine excretion rates were determined. Random urine samples from 36 patients with a variety of functional and pathologic renal disorders were assayed for the HRTE-1 antigen. Twenty-three of 24 patients with either chronic nephropathy or pre-renal azotemia had normal urinary antigen concentrations, despite wide differences in urine flow rates, the degree of existing renal function, and the amount of proteinuria. Ten of 12 patients with acute tubular necrosis, however, had statistically abnormal HRTE-1 concentrations (high in eight patients, undetectable in two). These findings suggest that HRTE-1 antigen can be detected in both normal and pathologic urines, that altered antigen concentrations can be documented in at least one renal disorder, and that quantitation of HRTE-1 in urine may have clinical value as a marker of acute rubular injury.

Studies on excretion of renal antigens in normal and pathological urine

The report deals with attempts to identify and quantitate renal antigens excreted into the urine of normal subjects and patients with renal disease. Although no useful information was obtained on the possible excretion of glomerular basement membrane antigens, renal tubular epithelial antigen (RTE) proved to be interesting. Curiously, massive excretion of RTE occurred most prominently in cases of 'minimal change' disease. In addition, a correlation between the selectivity of the proteinuria and excretion of RTE was noted. In general there did not seem to be any relation between RTE excretion and tubular/interstitial lesions.

Immunologic characterization of plasma membranes from the renal proximal tubule of the dog

Plasma membrane fractions from the brush border (BBM) and antiluminal (ALM) surfaces of the dog's renal proximal tubule cell were separated using free-flow electrophoresis. Rabbits immunized with BBM rapidly produced antibody, but rabbits immunized with ALM did not respond. Indirect immunofluorescence and immunoferritin studies showed that the antibody reacts with the brush border of the proximal tubules in the normal kidney of the adult dog. It also reacts with the surface membranes of certain other absorptive and secretory epithelia, such as gall bladder, small intestine, epididymis, and lacrimal gland. The antibody has affinity for the membrane maltase without affecting its catalytic activity, but does not appear to have affinity for the membrane alkaline phosphatase or the high affinity binding site for phlorizin present in the BBM. Polyacrylamide electrophoresis of solubilized BBM showed approximately 37 protein bands and four glycoproteins. We conclude that the proximal tubule cell is immunologically polarized with respect to the distribution of antigenic proteins, and that the BBM is highly antigenic. The antigenic components appear to be high molecular weight glycoproteins present in the glycocalyx.

Nephropathy associated with sickle cell anemia: an autologous immune complex nephritis. I. Studies on nature of glomerular-bound antibody and antigen identification in a patient with sickle cell disease and immune deposit glomerulonephritis

The nature of the glomerular-bound antibody and the putative antigen was investigated in one of the patients with sickle cell disease and immune deposit membranoproliferative glomerulonephritis by immunohistologic and glomerular antibody elution. Renal proximal tubular epithelial antigen was localized in association with immunoglobulins G (IgG), M (IgM), Clq fraction of the first component of complement (Clq) and the third component of complement (C3) in a granular pattern along the glomerular basement membrane of the patient's kidney. IgG and IgM were eluted from glomeruli. These immunoglobulins fixed to the proximal tubules of normal human kidney by direct immunofluorescence. This localization was abolished by absorption of the eluted immunoglobulins with renal tubular epithelial (RTE) antigen. The IgG eluted from the glomeruli blocked the fixation of rabbit anti-RTE antigen to normal proximal tubular brush border. These studies suggest that the nephritis in this patient was due to deposition of complexes or RTE antigen and specific antibody. An autologous immune complex nephritis may develop in some patients with sickle cell anemia secondary to RTE antigen released possibly after renal ischemia or some other phenomenon causing renal tubular damage.