Nephrotoxic nephritis in nude mice

We investigated the role of T cells in the pathogenesis of murine nephrotoxic nephritis (NTN). The disease was produced by injecting congenitally athymic nude (nu/nu) mice and their normal heterozygous (nu/+) littermates with rabbit anti-rat glomerular basement membrane (GBM) antiserum. Within 2-4 weeks we noted marked thrombotic lesions and depositions of mouse IgG, IgM, C3 and rabbit IgG along the GBM in both groups of mice. There was no significant difference in the extent of glomerular involvement between the two groups of mice. We conclude that T cell immunodeficiency plays no role in the development of severe glomerular lesions in murine NTN.

Localization of HLA-ABC and DR antigens in human kidney

Monoclonal antibodies to human monomorphic class I and class II major histocompatibility complex (MHC) determinants have been used with immunofluorescence and immunoperoxidase techniques, to localize these antigens in normal human kidneys. HLA-DR antigen was located in the glomeruli (probably on endothelium as well as the mesangium) and within the cells of cortical and medullary tubules. Dendritic cells in the renal interstitium stained brightly for the DR antigen and could be distinguished from the staining of capillary endothelium. The vascular endothelium of large vessels stained less densely for the HLA-DR antigen than for HLA-ABC antigens. The glomeruli stained intensely for the HLA-ABC antigens and diffuse staining of HLA-ABC antigens was also noted within renal tubular cells.

Major histocompatibility complex antigens in rat kidney, ureter, and bladder. Localization with monoclonal antibodies and demonstration of Ia-positive dendritic cells

Monoclonal mouse xenoantibodies to the SD and part of the Ia antigen complex of the rat major histocompatibility complex (MHC) were raised, and used to localize MHC antigens on frozen sections of kidney, ureter, and bladder of the DA rat strain. The Ia antigens recognized by our monoclonal antibody were located almost entirely within the cells of some, probably the proximal, convoluted tubules of the kidney. The only other Ia-bearing structures were intensely Ia-positive dendritic cells found predominantly in the renal cortex and in the mucosal connective tissues of the ureter and bladder. The SD antigens were widely distributed in the kidney with a major portion again located within the tubular cells, although in the case of SD antigens all tubular cells, including those of the medulla, were positive. By far the brightest tubules were clusters in the outer medulla, probably representing the thick loops of Henle. The endothelium of arterioles, venules and glomerular and interstitial capillaries all stained very brightly for SD antigens. The glomerular mesangium and the interstitial connective tissues of the kidney, ureter, and bladder all gave diffuse positive staining for SD antigens. Transplantation studies established that the tubular Ia and SD antigens of the kidney are produced by the cells and are not in the process of excretion or reabsorption.

The production of monoclonal antibodies against glomerular and other antigens of the human nephron

During our studies on human kidney tubular antigens we have applied the technique of cell fusion for the preparation of monoclonal antibodies. For this purpose, plasma membranes were prepared from human kidney cortex by homogenization, fractionated on density gradients and selected according to brush border marker enzyme activity. Spleen cells from Balb/c mice hyperimmunized with plasma membranes were fused (PEG) with NS1 plasmocytoma cells by standard procedure. Culture supernatants were tested for presence of specific antibodies by indirect immunofluorescence with fluorescein-conjugated rabbit anti-mouse Fab antibodies on human kidney slices. In two fusions (210 wells), 70 positive hybrids were found secreting antibodies for a variety of antigens in the kidney. Most of them were directed against tubular antigens. In addition, as a by-product, we detected hybridomas which secreted antibodies specific for antigens in other parts of the nephron, such as glomeruli, blood cloning, and monoclonal antibodies were produced in large amounts from ascitic fluid. Some of these antibodies are specific for antigens of the basement membrane, others for antigens of the mesangium. Some recognize antigens present on glomeruli alone, others recognize antigens present on glomeruli and tubules or on glomeruli and blood vessels. We are convinced that the new immunological technique will yield better information on the antigenic microstructure of the nephron. In addition, the monoclonal and, by definition, monospecific antibodies might be useful for diagnostic purposes: recognition and quantitation of the corresponding antigens in the serum and/or urine of patients suffering from kidney diseases.

Distribution of blood group antigen A in normal and pathologic human kidneys

We tested this distribution with an indirect immunofluorescent technique using purified rabbit anti-A antiserum on 21 whole normal kidneys (a group, N equal to 18; AB group, N equal to 1; O group, N equal to 2) and on 349 kidney biopsy samples (A group, N equal to 140; AB group, N equal to 14; O or B group, N equal to 195) representing a large spectrum of renal diseases. In normal kidneys from A and AB groups, the A antigen was detected in the whole vascular endothelium and in the convoluted distal tubules. In secretors, collecting tubules were brightly positive. Epithelial staining was more diffuse in the inner part than it was in the outer part of the medulla. The basement membrane of the inner collecting tubules was positive in frozen sections but not in paraffin sections. In pathologic kidneys, modifications were obvious: (1) The thickened basement membrane of atrophic convoluted distal tubules was brightly stained. (2) Endothelial staining allowed a precise appreciation of the glomerular and interstitial vasculature. (3) In proliferative changes such as arterial intimal proliferation, proliferative glomerulonephritis, and interstitial cell infiltration, endothelial cells do not proliferate. This routine staining technique of endothelial cells by anti-A antiserum provide information not obtainable with light microscopy.

Fluorescent studies on the potential existence of vascular metallic immune complexes

Renal arteriolar thickening, which occurs in response to the presence of cadmium ions, was investigated by fluorescent microscopy. In an acridine orange-stained preparation of the rat kidney, positive fluorescence was observed in the media of renal arterioles following long-term implantation of cadmium wire into the cortex, but was absent in animals similarly treated with copper wire or plastic. The presence of lymphocytic foci around the thickened vessels in cadmium-containing kidneys, together with recent evidence pointing to an association of RNA with immune complex formation, would suggest that the vascular thickening in the presence of cadmium ions is attributable, at least in part, to the mural location of a metallic-originated immune complex.

Effects of antibody to renal plasma membrane on urinary excretion of adenosine 3',5'-monophosphate and phosphate induced by parathyroid hormone infusion in rats

Studies were made on the effects of pretreatment of rats with antibody to renal cortical plasma membrane (anti-RPM) on the urinary excretion of cAMP and phosphate induced by infusion of parathyroid hormone (PTH). With PTH infusion, the increase in the urinary excretion of cAMP and phosphate were not parallel. Infusion of 1-40 mg anti-RPM inhibited PTH-induced increase in urinary phosphate excretion but not the increase in urinary cAMP. Infusion of 100 mg of anti-RPM inhibited PTH-induced increases in the excretion of both substances. Infusion of nonimmunized rabbit immunoglobulin (IgG; normal IgG) did not affect PTH-induced increases in the excretion of either cAMP or phosphate. In vitro in isolated renal tubules, with 10 mg/ml anti-RPM, the increases in cAMP content induced by PTH were significantly less than those seen with lower concentrations of this antibody or with normal IgG.

Murine autoimmune interstitial nephritis and associated antigen: purification of a soluble tubular basement membrane antigen from mice kidneys

A soluble tubular basement membrane (TBM) antigen has been purified from murine kidneys. The isolated fibers were trypsinized and subjected to zone electrophoresis, Sephadex G-200 gel filtration, and DEAE-cellulose chromatography eluted with linear NaCl concentration gradient while monitoring the TBM antigen activity with specific antihuman TBM antigen. The molecular weight of TBM antigen was estimated to be 30,000 daltons by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified TBM antigen gave a single precipitin line against the specific antiserum and cross-reacted with the TBM antigen similarly purified from other animals such as goat, guinea pig and also with human TBM antigen in an immunodiffusion plate. BALB/c, C3H/He and C57BL/6 mice were immunized twice at 2 weeks' interval with the TBM antigen and adjuvant. Histologically typical interstitial nephritis occurred in BALB/c mice, whereas no nephritis developed in other strains of mice. The inflammatory changes were characterized by intense mononuclear cell infiltration, tubular destruction, and interstitial and periglomerular fibrosis. The serum-stained basement membrane of normal tubules and Bowman's capsules, and no antiglomerular basement membrane activity was detectable in the serum by immunofluorescence. This system provides a simple and useful model in interstitial nephritis in mice produced with a purified TBM antigen.

Human basement membrane antigens from lung, placenta and kidney

Three human basement membranes, glomerular basement membrane (GBM) from renal cortex, alveolar basement membrane (ABM) from lung parenchyma and trophoblast basement membrane (TBM) from the terminal villi of placenta have been isolated by sieving and sonication techniques. Canine GBM and ABM were also prepared. There were marked differences among the membranes from human tissues. Compared to GBM, TBM had very little collagen but contained high concentrations of charged amino acids. ABM was intermediate in composition between GBM and TBM and contained desmosine and isodesmosine indicative of the presence of elastin. Canine ABM (c-ABM) did not contain desmosine or isodesmosine. In the canine system an antigen was detected in ABM which was not present in GBM. The membrane preparations were analyzed for fibronectin content using a specific antiserum to fibronectin. This glycoprotein could not be detected in GBM whereas it was present in ABM in amounts up to 0.8% and in TBM in amounts as high as 7.2%. All the membranes induced the formation of precipitating antibodies in rabbits. Soluble material obtained from the membranes by alkali extraction, reduction of disulfide bonds, enzymatic digestion with elastase, plasmin or collagenase provided immunologically reactive fragments. These soluble fragments gave reactions of identity among the three basement membranes in immunodiffusion reactions in gels with antisera raised to all three BMs. The finding that plasmin digests basement membranes suggests that it may play a role in connective tissue remodeling. The fact that elastase degrades basement membranes provides an endogenous system for injury which may be triggered by infections.

Specificity and nephrotoxicity of heterologous antibodies directed against renal basement membranes

Two immune sera have been raised in sheep against rabbit glomerular and tubular basement membranes, respectively (GBM and TBM). Their specificity was investigated by immunoabsorption and radioimmunoassay, and their nephrotoxicity was studied by injecting them into New Zealand rabbits. Both antisera reacted in vitro collagen and noncollagen-related glycopeptides. However, while the anti-GBM antiserum reacted preponderantly with GBM and TBM collagen which probably represent the antigen(s) shared by the two basement membranes, the anti-TBM antiserum was directed preferentially against the noncollagenous component of rabbit TBM. The anti-GBM antiserum induced in rabbits a diffuse extracapillary glomerulonephritis with linear fixation of autologous IgG and C3 along the GBM. The anti-TBM antiserum also induced an extracapillary glomerulonephritis but in addition a focal tubular atrophy was seen and autologous IgG and C3 were fixed along both GBM and TBM and glucosuria frequently occurred. These results suggested that the glomerular lesions induced by the two antisera were due to anticollagen antibodies while the tubulointerstitial lesions were due to antibodies directed against the noncollagenous portion of TBM.

Some hemodynamic determinants of immune complex trapping by the kidney

This study was undertaken to help clarify the relationship between capillary hemodynamic events and the tissue uptake of circulating immune complexes (IC). In each of 23 dogs, bovine serum albumin (BSA) and rabbit antiBSA soluble IC labeled with 125I were given by constant i.v. infusion, and IC uptake by a normally perfused kidney was compared to that of the contralateral kidney in which renal blood flow (RBF) was changed by renal artery constriction or raised ureteral pressure. In these same animals, IC uptake in 15 other major organ systems was also measured simultaneously. During IC infusion microspheres of 85Sr were injected to measure cardiac output and tissue blood flow, and red cells labeled with 51Cr were infused to mark tissue vascular volume. At completion of the IC infusion, tissue samples were taken from the kidneys and the 15 other major organs systems. From the isotope content of each tissue, we determined IC content, blood flow rate, vascular transit time, and fractional uptake of IC (FIC). In addition, glomeruli were isolated from renal cortex to assess IC uptake in glomerular versus renal nonglomerular tissue. We found that 1) for kidney, IC delivery rate, capillary hydrostatic pressure, and capillary ultrafiltration rate are less important than the plasma IC concentration in determining IC uptake; 2) for each organ studied, the principal determinant of IC uptake per gram of tissue, at any given PIC, is vascular volume per gram of tissue; 3) tissue vascular volume per gram of tissue may determine IC uptake per gram of tissue because tissue vascular volume determines the capillary surface area in contact with circulating IC or because tissue vascular volume determines tissue vascular transit time, at any given tissue blood flow rate.

Demonstration of antinuclear antibodies in mercuric chloride-induced glomerulopathy in the rat

Serial administration of mercuric chloride to PVG/C rats induced a glomerulopathy associated with immune complex deposition along the glomerular basement membrane and in the mesangial area. These deposits could be demonstrated by immunofluorescence and electron microscopy 5 to 8 weeks after the first injection of mercuric chloride. At this time antinuclear antibodies could be demonstrated in the sera and in the eluates from the renal cortices from diseased animals. These findings suggest a possible role for antibodies directed against nuclear antigen in the pathogenesis of this type of experimental glomerular disease.

Neutralization of meningococcal endotoxin by antibody to core glycolipid

Antibodies to Escherichia coli J5, a uridine 5'-diphosphate-galactose epimerase-less mutant of E. coli 0111, neutralized meningococcal endotoxemia from all three major capsular serogroups. We chose the dermal necrosis of the local Shwartzman phenomenon and the renal cortical necrosis of the general Shwartzman phenomenon as assays because these are the hallmarks of meningococcemia, and because meningococcal lipopolysaccharide (LPS) is a uniquely potent cause of dermal purpura and necrosis. Meningococcal antisera raised against LPS from MGC A, B, and C also provided good protection against endotoxemia from the homologous capsular groups, but it was inconsistent against the heterologous serogroups. The superiority of J5 antibodies (purified IgG as well as antiserum) is probably due to the fact that J5 LPS contains only the endotoxin core. Consequently, immunization with this mutant stimulates production of antibodies to core LPS without interference by the "0" antigenic determinants of the side chains. These observations indicate that the endotoxin core is the toxic moiety of meningococcal LPS, that the core LPS of meningococcus (MGC) is immunologically similar to enteric LPS, and that the antigenically variable "0" side chains of MGC LPS interfere with antibody production against the common core. They also suggest that antibodies prepared against this E. coli mutant could interrupt the devastating course of meningococcal endotoxemia in man, regardless of the capsular serogroup of the infecting strain.

A new pattern of non-organ- and non-species-specific anti-organelle antibody detected by immunofluorescence: the mitochondrial antibody number 5

About 0.1% of the sera in human pathology produce a peculiar, cytoplasmic, non-organ- and non-species-specific fluorescence. This may easily be differentiated from the already described anti-organelle antibodies and, more particularly, from the mitochondrial antibodies of primary biliary cirrhosis. Should rat tissues be used in the immunofluorescence test, fluorescence predominates over the first two portions of the renal proximal tubules (P1 and P2) and the mucous neck cells of the stomach. This pattern may be atrributed to mitochondria, and in particular to their inner membranes by fluorescent staining of the ellipsoid region of the rods and cones of the eyes, and by absorption with purified organelles. To distinguish this antibody from the already described mitochondrial antibodies, this one will be called mitochondrial antibody number 5 (M5). The seven carriers of this antibody suffer from systemic lupus erythematosus or autoimmune haemolytic anaemia. In these cases no diseases of the liver were observed, contrary to other classical mitochondrial antibodies.

Prostaglandin: increased production by renal cell carcinoma

The syndrome of hypercalcemia in patients with renal cell carcinoma without metastasis to bone, in association with elevated levels of immunoreactive prostaglandin E and normal parathyroid hormone levels, prompted the investigation of an etiologic relationship of increased prostaglandin in this syndrome. Ethyl acetate extracts of tissue culture effluents, primary and metastatic renal cell carcinoma, and plasma were chromatographed on silicic acid columns and assayed by double antibody immunoprecipitative methods for immunoprecipitative methods for immunoreactive prostaglandins A and E. Increased levels of immunoreactive prostaglandins A and E were found 1) to be generated in parallel with cell growth during a period of time by renal cell carcinoma in monolayer growth, 2) in extracts of primary and metastatic renal cell carcinoma tissue and 3) in the venous effluent of a kidney bearing a renal cell carcinoma. These findings support the hypothesis that renal cell carcinoma can produce prostaglandins. Furthermore, reported syndromes of patients with renal cell carcinoma associated with elevated prostaglandin levels may result from the autonomous production of prostaglandins in vivo by the tumor.

Regulation of compensatory kidney hypertrophy by its own products

1. The ligation of blood vessels of one kidney of adult rats resulted in the compensatory hypertrophy of the other kidney. In most animals the rate of hypertrophy was indistinguishable from that observed after unilateral nephrectomy, but in a few cases the onset was retarded when the renal artery alone had been ligated and the collateral circulation increased.2. When the blood vessels of one kidney of adult rats were ligated and the cortex was excised, the rate of compensatory renal hypertrophy was similar to that observed after unilateral nephrectomy.3. In animals operated for simultaneous partial hepatectomy and unilateral nephrectomy, there was no sign of compensatory renal hypertrophy while the liver was undergoing regeneration. Renal hypertrophy started after 7 days, when about 98% of the amount of liver removed had been regenerated.4. Neither aseptic autolysis of one kidney following suppression of its blood supply, nor unilateral nephrectomy affected the rate of liver regeneration after simultaneous partial hepatectomy.5. Total splenectomy did not affect the rate of compensatory renal hypertrophy following unilateral nephrectomy.6. The heterotopic graft of renal cortical, but not of medullary, cells inhibited compensatory renal hypertrophy in adult rats. The removal of the graft after 14 days was followed by the resumption of compensatory hypertrophy.7. The inhibiting action of fractions of renal cortical extracts fractionated on Sephadex G100 resin and DEAE-52 cellulose were assayed on the ;growth' of renal explants reared in vitro. The final material, though only partially purified, proved to have an inhibiting activity between 250 and 500 times greater than that of the initial extract.8. When injected into unilaterally nephrectomized rats, the partially purified extract from the renal cortex had an inhibiting effect on compensatory renal hypertrophy.9. Immunofluorescence technique showed that the partially purified cortical extract affected the proximal convoluted tubes specifically, irrespective of animal species.

Chronic one-kidney hypertension in rabbits. III. Renopressin, a new hypertensive substance

The blood pressure of rabbits with chronic one-kidney hypertension can be lowered to normal by immunization with hog kidney cortex preparations that do not contain renin, thus providing evidence for a new factor essential for the maintenance of an elevated blood pressure. A search for the new factor has led to the discovery of a hypertensive substance which we have named renopressin. Subcutaneous injection of the new substance into normal rabbits produces a delayed, slow increase in blood pressure, and after a few days the development of a moderate hypertension which persists indefinitely. The response of the blood pressure to renopressin is totally unlike that to renin. While the pressor action of renin can be blocked by an angiotensin II antagonist, the hypertension caused by renopressin cannot. Renin can increase the blood pressure of hypertensive rabbits; renopressin has no effect. The blood pressure of hypertensive rabbits and of normal rabbits made hypertensive by injection of renopressin can be lowered to normal by passive immunization with the same antibody preparation. The evidence is consistent with the possibility that renopressin and the agent causing the elevation of blood pressure in hypertensive rabbits are similar or identical.

Demonstration of human nephritogenic tubular antigen in the serum and organs by radioimmunoassay

Nephritogenic tubular epithelial antigen (Tub-Ag), which had been found in immune complexes deposited along the glomerular capillary walls of some patients with idiopathic membranous glomerulonephritis, was solubilized from renal tubuli of humans by Pronase digestion. Soluble Tub-Ag was then purified by gel filtration and ion exchange chromatography on DEAE-Sephadex. Three DEAE fractions, designated as 0.07 M, 0.13M, and 0.23 M fractions, raised antibodies in rabbits and fluoresceinated antibodies against any of these fractions reacted exclusively with luminal layer of proximal tubular epithelia. Among three fluoresceinated antibodies, however, only the one directed to 0.07 M fraction bound with immune complexes which were deposited along the glomerular capilary walls of the patients with Tub-Ag (DEAE 0.07 M fraction) was physicochemically homogenous with a S20 value of 8.2. Utilizing 125I-labeled Tub-Ag, a sensitive and quantitave radioimmunoassay of Tub-Ag was developed. Tub-Ag was demonstrated to occur naturally in serum and urine, as well as in all the organs tested including kidney, intestine, liver, spleen, stomach, heart, and lung. Tub-Ag was detected even in the sera of anephric patients on maintenance hemodialysis (60.8 +/- 7.8 radioimmunoassay units/ml), although at slightly lower levels than in those of normal individuals (69.9 +/- 10.6 units/ml). The size of serum Tub-Ag was identical to that of molecules bearing Tub-Ag activity solubilized by Pronase from all the organs tested, indicating that circulating Tub-Ag was maintained mainly by organs other than kidneys.

Chronic one-kidney hypertension in rabbits. II. Evidence for a new factor

The arterial pressure of rabbits with chronic one-kidney hypertension can be lowered to normotensive levels by direct immunization with preparations made from the cortex of hog kidneys. Hypertensive rabbits that are immunized with large amounts of renin may develop high plasma antirenin titers without affecting their blood pressure. Removal of renin by chromatography on columns of immobilized antirenin yields preparations with little or no renin. Such preparations may be effective in lowering blood pressure although they do not elicit the formation of plasma antirenin and the rabbits remain sensitive to challenging doses of rabbit renin. The evidence suggests that an unknown substance is responsible for the development of a cross-reacting antibody that neutralizes an unknown factor that is essential for the maintence of an elevated blood pressure level in rabbits with chronic one-kidney hypertension.

Depression of the T-lymphocyte response to phytohaemagglutinin by renal cells

The lymphocytic infiltrate in the renal parenchyma is a consistent histological feature of pyelonephritis, but the role of the lymphocytes in the immunobiology of pyelonephritis is not known. In this investigation the influence of the local environment on the potential function of T lymphocytes in the kidney was investigated. The experiments have demonstrated that the response of rat lymphocytes to stimulation in vitro with phytohaemagglutinin (PHA) can be entirely ablated by normal kidney cells. Even when the number of kidney cells added to cultures of lymphocytes was less than 2% of the cells present some ablation of T-lymphocyte function could be detected. The biological characteristics of the factor causing ablation of the PHA responsiveness of T lymphocytes were partially characterized and the factor appears to have unique features that differentiate it from lymphocyte chalones and other tissue factors influencing lymphocyte function. The results may explain recent findings where T lymphocytes were found to be the predominant lymphocyte in the inflammatory infiltrate but were not responsive to PHA in vitro.

Mesangiocapillary glomerulonephritis in lambs. III. Quantitative and qualitative aspects of immunopathology

Newborn Finnish Landrace lambs subsequently affected with mesangiocapillary glomerulonephritis (MCGN) were deficient in the third component of complement (C'3), serum levels being approximately 5 per cent. of those in unaffected lambs. Hypocomplementaemia persisted until symptoms of renal failure occurred at around 6-8 wk of age. Immunofluorescence examinations of renal cortex with antisera specific for IgG, IgM, IgA, C'3 and fibrin supported previous morphological evidence of a strong similarity between this disease and MCGN in man. Similar examinations of choroid plexus suggested that immune complexes containing IgG, IgM and C'3 were present in the interstitium.

The electron microscopic localization of nephrotoxic antibodies in isolated glomeruli

Scanning electron microscopy showed that most glomeruli isolated by sieving from normal and nephrotoxic rats were cleanly decapsulated and undisrupted. An anti-IgG antibody-horesradish peroxidase conjugate was applied to such isolated glomeruli and also to slices of renal cortex which were sebsequently embedded in epoxy resin. Linear staining along the glomerular basement membranes of nephrotoxic rats was evident and subendothelial electron-dense deposits were shown to contain anti-glomerular basement membrane antibody. Whereas the linear reaction was faint and limited to superficial parts of glomeruli in tissue slices, it was intense and present in most regions of all of the isolated glomeruli. Thus, the fine details of the distribution of intraglomerular antibody are more clearly and consistently demonstrated in isolated glomeruli than in kidney slices.

Immunologic enhancement of rat renal allografts. III. Immunopathologic lesions and rejection in long-surviving passively enhanced grafts

Immunologic enhancement of renal allografts from (Lewis times Brown Norway) F1 to Lewis rats was achieved by administering a single dose of antidonor serum at the time of transplantation. A series of grafts functioning for 1 to 4 months after transplantation were examined by light and immunofluorescence microscopy to evaluate the long-term protective effects of the enhancing serum and to determine if previously unobserved lesions appeared in long survivors. Despite the absence of detectable circulating cytotoxic alloantibody, long-term allografts showed necrotizing glomerular and arterial lesions which resembled those seen in acutely rejecting grafts and were compatible with humoral rejection. Thus, in this model, there is a late decline in the ability of passive enhancement to inhibit humoral rejection. Long-term grafts also developed tubular lesions with deposition of immunoglobulin and complement on the tubular basement membranes (TBM). Anti-TBM antibodies were demonstrated in recipients' sera and found to be organ specific but not major histocompatibility antigen or species specific. This tubular lesion is therefore a unique form of allograft injury in which the immune response is directed against tissue antigen(s) which are distinct from the major histocompatibility antigens that induce rejection.