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The human complement system is comprised of 19 plasma components and regulatory proteins and of at least 9 distinct cellular receptors for these proteins or their activation fragments. The important role of complement in host defense against infection is related to its capacity to opsonize microorganisms, lyze target cells, and induce the release of inflammatory mediators from leukocytes. Complement participates in the processing and clearance of immune complexes and in regulation of the immune response. Most of the biologic effects derived from complement activation depend on ligand-receptor interactions between complement proteins or their cleavage fragments and specific receptors on cells. Two types of ligands are generated during complement activation: soluble low-molecular-weight ligands, such as the anaphylatoxins C3a and C5a, and so-called bifunctional ligands that attach both to the target of complement activation (opsonins) and to the appropriate receptor on effector cells. The most abundant complement protein in plasma is C3. Activation of the classic and alternative complement pathways generates C3 convertases that cleave C3 into an anaphylatoxic fragment, C3a, and a major fragment, C3b, which is capable of forming a covalent linkage with the targets of complement activation. Surface-bound C3b is the preferential ligand for the C3b receptor, CR1 (CD 35), which is expressed on most peripheral blood cells. The receptor plays an important role in the processing of immune complexes, the phagocytosis of C3b-bearing microorganisms, and regulation of the immune response. The cellular expression of the molecule is decreased in patients with systemic lupus erythematosus (SLE) and in patients infected with the human immunodeficiency virus (HIV).

The renal distribution of autologous and heterologous albumin and IgG was studied by electron microscopy using peroxidase-labeled conjugates in rats with Heymann nephritis. In addition, the renal distribution of autologous and heterologous antiperoxidase IgG and their F(ab')2 and Fab fragments was detected using peroxidase alone. All of these proteins crossed the glomerular lamina densa and passed into the urinary space by an extracellular pathway through the epithelial slits and the sites of epithelial detachment. The proteins were trapped in subepithelial immune deposits irrespective of the degree of proteinuria and regardless of the molecular weight, the autologous or heterologous origin, and the electric charges of the protein studied. The trapping was transient and easily reversed. These findings suggest that circulating proteins are able to modify the composition of immune deposits, thereby altering the course of immune complex disease.

A few cases of improvement in secondary renal amyloidosis following surgery (in particular, removal of the amylogenic foci) have been published, but cases of aggravation are much more numerous. The authors report on three patients whose renal function deteriorated dramatically after extra-renal surgery (pneumonectomy, aortic valve replacement, mitral valve replacement). None of the usual precipitating factors, such as DIC, cardiovascular collapse, sepsis or renal vein thrombosis, could be detected, but two patients had been under extracorporeal circulation. Such accidents appear to be unpredictable and irreversible. They can be seen in primary or secondary amyloidosis and whether or not surgery involves an amylogenic focus. Indeed, in two of their patients the diagnosis of amyloidosis was unknown before the operation. This suggests that in patients with suspected amyloidosis no major surgical operation should be undertaken without prior renal biopsy.

A novel association in the same patient with small lymphocytic lymphoma, type II cryoglobulinemia and glomerulonephritis is reported. This case is also characterized by a quite unusual sequence of glomerular alterations. A first renal biopsy showed severe endocapillary proliferative glomerulonephritis due to monocytic infiltration without any evidence of deposition of immune reactants. The immune deposits associated with type II cryoglobulinemia were only observed at a second renal biopsy performed five months later. This case shows that mononuclear cells can be responsible in and of themselves for severe glomerular damage, without deposition of immune material, and suggests that monocytic infiltration might be the first stage of type II cryoglobulinemia associated glomerulonephritis.

A case of massive amyloidosis without detectable monoclonal Ig component either in serum or in urines on classical electrophoresis and without obvious plasma cell proliferation is reported. Immunohistochemical study of renal and bone marrow biopsies showed that amyloid deposits were specifically stained with the anti-lambda antiserum and that 92% of the plasma cells were also lambda positive. Immunofixation following electrophoretic analysis of serum and urinary proteins exhibited a monoclonal lambda light chain at an advanced stage of the disease. Simple but not routinely used techniques are therefore of great interest to characterize apparently idiopathic amyloidosis which could have therapeutic implications.

Three renin-secreting juxtaglomerular cell tumors were studied by ultrastructural and immunocytochemical methods. Both active and inactive renins were identified in tumor extracts. By immunofluorescence and the peroxidase-antiperoxidase (PAP) method with antirenin antiserum, immunolabeling was intracytoplasmic and irregularly distributed throughout the tumor tissue. Electron microscopic examination revealed various types of secretory granules, including atypical giant crystalloid protogranules in one case, and the postembedding PAP procedure showed labeling of all types of granules. Acid phosphatase staining was observed within secretory granules and autophagic vacuoles. The process of renin storage and release is discussed. The presence in one case of a neural component and a distal tubular structure supports the view of a hamartomatous lesion.

Decreased factor VIII von Willebrand activity in contrast with increased factor VIII procoagulant activity and increased concentrations of factor VIII related antigen, were found in the plasma of patients with chronic renal failure. This functional abnormality of the factor VIII protein is not improved by haemodialysis, but it is no longer found in patients with normally functioning grafted kidneys. It may at least partly explain the prolonged bleeding time commonly found in chronic renal failure.

The expression of complement receptor antigens by human Kupffer cells (KC) was investigated by immunohistochemical techniques in seven normal human liver biopsies. Polyclonal and monoclonal antibodies were revealed by double labeling of cells using indirect immunofluorescence and immunoenzymatic techniques or by using double immunoenzymatic techniques. In most experiments, one antigen was revealed by streptavidin-biotin-peroxidase complexes whose reaction product was examined by light microscopy and the second antigen stained using the alkaline phosphatase antialkaline phosphatase method visualized by fluorescence microscopy using fluorescein isothiocyanate or tetramethylrhodamine isothiocyanate filters. KC were identified using monoclonal antibody EBM11 that recognizes 100% of KC in hepatic lobules and was paired with each antibody directed against complement receptors. CR1 and CR3 (alpha- and beta-chains) were found to be the predominant receptor antigens expressed by human KC. CR4 (p150,95) was expressed on all KC, but staining with anti-CR4 monoclonal antibodies was consistently weaker than that observed with anti-CR3 antibodies. No staining of KC was observed with anti-CR2 (CD 21) antibodies. Expression of CR1, CR3, and CR4 complement receptors on KC provides the cells with an optimal capacity to bind and phagocytize particles or immune complexes coated with any type of ligands for C3 receptors.

The presence and distribution of Ia antigen in normal human kidneys and biopsy specimens from patients with renal disease were investigated by immunohistochemical techniques using two monoclonal antibodies to the nonpolymorphic determinants of human HLA-DR molecules. Ia antigen was found on the endothelium of glomerular and peritubular capillaries and of veins and vasa recta. Loss of endothelial staining was found in necrotic and sclerotic glomerular and tubulointerstitial lesions. Staining or decreased staining was also not found in the severe proliferative nephritis of systemic lupus erythematosus although endothelial cells could still be identified upon light microscopic examination of the same biopsy specimen. Resting and proliferating cells in mesangial areas did not stain with anti-Ia antibody and extracapillary proliferating cells did not express Ia antigen except for occasional cells in anti-GBM crescentic glomerulonephritis, suggesting that Ia-bearing cells are not involved in mesangial and most extracapillary proliferations in human glomerulonephritis. All clustered mononuclear cells infiltrating the renal interstitium stained with anti-Ia antibody regardless of the type of nephritis where infiltrates occurred.

An illustration of the ocular involvement seen in Fabry's disease: cornea verticilata, vascular conjunctival lesions, dyschromatopsia was observed in two brothers who were carriers of the condition.

A new technique for experimental reversible hydronephrosis in the rat was developed. A noninvasive radioisotopic investigation, using Tc-99m dimercaptosuccinic acid, permitted sequential assessment of the separate renal function at different stages of the study. After 1 week of unilateral ureteral obstruction, reversibility was obtained by the removal of the obstructive device. Ten days after the obstruction release, the ipsilateral kidney had returned to 71 per cent of its preligation uptake value. Histological findings demonstrated the reversibility of the surgical obstruction.

The distribution of renin was investigated by immunofluorescence in human kidney biopsy specimens (27 patients with lipoid nephrosis, 39 with Berger disease, 17 with membranous glomerulonephritis, 5 with thrombotic microangiopathy, and 7 with malignant nephroangiosclerosis). A semiquantitative assessment was carried out. Two ratios were found significatively increased in the study groups as compared with the control group: JGA + and JGA ++ which expressed, respectively, the number of fluorescent JGA in relation to the number of glomerular sections and the number of fluorescent JGA with more than six renin-containing cells (RCC) in relation to the number of immunoreactive JGA. Highest values were observed in patients with thrombotic microangiopathy and malignant nephroangiosclerosis (P less than 0.001). The above immunomorphological parameters were correlated with clinical and laboratory data. A positive dependency was found between JGA + and JGA ++ ratios and a low sodium diet, diuretic therapy and serum creatinine. A negative dependency was seen in the albumin and hemoglobin serum levels. No correlation was found with blood pressure values. These observations suggested that decreased plasma volume and impaired renal function could be factors leading to an increased renin production in the kidney.

The antihypertensive, renal and hormonal effects of captopril were studied in 10 patients with essential hypertension. Captopril significantly decreased arterial blood pressure with a concomitant increase in glomerular filtration rate, natriuresis and kaliuresis and a significant selective increase in urinary (renal) prostaglandin E2; other plasma and urinary prostaglandin (F2 alpha, 6-keto-prostaglandin F1 alpha; thromboxane B2) were not significantly changed. The urinary prostaglandin E2 increase was observed even in patients with pretreatment subnormal prostaglandin E2 excretion. Increases in urinary prostaglandin E2 were significantly positively correlated with increases in urinary sodium concentration. It is concluded that the antihypertensive effect of captopril is mediated, at least partially, by prostaglandin E2 release from renal and extrarenal tissues. Captopril enhances natriuresis at a lower perfusion pressure.

A radioimmunoassay method, using highly specific and sensitive rabbit antiserum, for the measurement of thromboxane (Tx)B2 in human plasma and urine, is described. Assay sensitivity was 5 pg; 50% displacement was achieved by 41 pg of cold TxB. Intra-assay variability was 10% and interassay variability 8,5%. Preliminary extraction and chromatography were necessary as direct radioimmunoassay of plasma although possible, was not reliable. The measurement of TxB2 reflects closely the synthesis of TxA2. The peripheral venous plasma TxB2 concentration in 13 young healthy volunteers (mean age 28 +/- 2 years) was 35 +/- 8 pg/ml; it was significantly higher in 14 older subjects (mean age 45 +/- 5 years) 101 +/- 14 pg/ml (p less than 0.001). Urinary TxB2 excretion was 141 +/- 15 pg/min in the younger group and 220 +/- 39 pg/min in the older group of normotensive subjects. There was a significant positive correlation between urinary TxB2 excretion and age (p less than 0.001). The increase with age of plasma and urinary TxB2 in man may have a pathophysiological importance.

The underlying mechanism of human extramembranous glomerulonephritis (EMGN) is generally thought to involve circulating immune complexes. Data presented here suggest that "in situ" formation of immune deposits may also be important in the pathogenesis of EMGN. We describe a patient with a "de novo" EMGN in a kidney transplant a few months after the graft placement. Before transplantation, the patient's serum contained antibodies reacting in vitro with rat kidney brush-border, but serum concentration of these antibodies rapidly decreased prior to the onset of proteinuria. No circulating immune complexes were detected on serial serum samples from the patients. Antibodies which were eluted from the kidney transplant biopsy were shown to react with the brush-border of the proximal convoluted tubule of rat kidney. We postulate that "in situ" formation of immune complexes within the glomerular capillary walls, and not circulating immune complexes, is the pathogenic mechanism responsible for the glomerular lesions of this case of EMGN.

A young adult patient had an unusual acute idiopathic nephrotic syndrome. This nephrotic syndrome was remarkable for (1) association with acute renal failure and hypertension, (2) finding of minimal glomerular changes with a linear fixation of the anti-human IgG conjugate along the glomerular capillary wall without demonstrable antiglomerular basement membrane antibodies, and (3) complete recovery, including disappearance of the linear staining, after treatment with prednisone, cyclophosphamide, and plasmapheresis.

The distribution of renin in human kidney was investigated by immunofluorescence and the peroxidase-antiperoxidase (PAP) procedure at the light and ultrastructural level. In three cases of juxtaglomerular renin-secreting tumors, renin was localized within the cytoplasm of tumor cells. In kidney biopsies, a semi-quantitative assessment was carried out, taking into account the size and the number of immunostained juxtaglomerular apparatuses. In 12 cases of ischemic kidneys and 8 cases of segmental renal hypoplasia, the increase in immunostaining for renin was striking in altered areas, while spared areas remained negative. In 2 cases of Bartter's syndrome, the pattern was similar to that found in ischemic kidneys. The study was extended to a series of 133 needle kidney biopsies from patients with various glomerular and vascular diseases; the immunomorphological parameters were correlated with serum creatinine levels but not with blood pressure values. Post-embedding immunoelectronmicroscopy using the PAP procedure performed on two of the cases of renin-secreting tumors, showed renin in all types of secretory granules.

Platelets and intravascular coagulation are involed in the pathogenesis of renal allotransplant rejection phenomena: fibrin deposition is a prominent feature of hyperacute rejection; arteriolar microthromboses when they are present, worsen the prognosis of an acute reversible rejection; the organisation of platelets and fibrin deposits on the intima may lead to the "endarteritis obilterans" of chronic bascular rejection. The interactions between endothelium, platelets, coagulation, fibrinolysis and cellular or humoral effectors of the immune respone were studied and special reference was made to their role in vascular rejection. The poor prognosis in vasuclar lesions justifies therapeutic trials with drugs inhibiting the early events of thrombogenesis.

Thirty-four patients with overt glomerulonephritis and chronic liver disease were studied. Kidney specimens were examined by light, electron and immunofluorescence microscopy. Plasma C3 levels were measured and a search for cryoglobulinemia was carried out in all patients. Twenty-six out of the thirty-four patients had an immune complex type glomerulonephritis (membrano-proliferative glomerulonephritis or glomerulosclerosis with mesangial deposits) suggestive of hepatic glomerulonephritis. The glomerular deposits almost always contained IgA and very frequently other immunoglobulins as well as C3. The membrano-proliferative glomerulonephritis was characterized by severe renal symptoms, mixed cryoglobulinemia and the frequent finding of low C3 levels. These data suggest that there is a linkage between liver disease and glomerulonephritis. The immunomorphological type of glomerulonephritis and the cryoglobulinemia are both suggestive of an immune complex disease. The lowering of the C3 levels could be due to activation of complement components by immune complexes, to hepatic hyposynthesis, or to a combination of the two.

Aldosterone injected i.m. decreased the release of renomedullary PGEs and the index (urinary Na/K ratio) in conscious normotensive intact and adrenalectomized rats. Coadministration of spironolactone increased the release of PGEs as well as the index (urinary Na/K ratio). The effect of spironolactone was partly inhibited by aspirin injected in a ratio 5:1 (aspirin:spironolactone), and effect which could be reversed by the infusion of a synthetic prostaglandin (PGA2) in a subhypotensive dose.

The distribution pattern of the C3b receptor (CR1) antigen, one of the earliest differentiation markers of the podocyte plasma membrane, has been studied during human renal ontogenesis by indirect immunofluorescence and immunoelectronmicroscopy using Fab'2 fragments of anti-CR1 antibodies. CR1 antigen has been detected at the open-stage glomerulus, which precedes constriction of the vascular pole, along the capillary wall, in a thick and homogeneous pattern of staining. By immunoelectronmicroscopy, CR1 antigen was present on the porocyte plasma membrane towards the glomerular basement membrane (GBM), and diffusely distributed within the GBM according to a decreasing intensity gradient from podocytes to endothelial cells. At a later stage of differentiation ('closed' glomerulus stage) when constriction of the vascular pole has occurred, the podocyte plasma membrane appeared diffusely labelled for CR1; the GBM was also stained with a decreasing intensity gradient from podocytes to endothelial cells. This result indicates that a plasma membrane receptor belonging to the cell coat of podocytes can be found in the extracellular space within the GBM. Thus the antigenic repertoire of the GBM of human fetal kidney comprises antigens of constituent molecules of the extracellular matrix and planted antigens originating from adjacent cells.

The localization of S protein (Vitronectin) antigen was studied by indirect immunofluorescence and immunoelectron microscopy in normal adult human kidneys and in biopsy specimens from patients with a wide range of renal diseases, and compared with that of neoantigens of the C5b-9 terminal complement complex. S protein antigen was diffusely present in arteriolar perimyocytic matrices, the glomerular basement membrane and mesangial matrix, and tubular basement membranes in the cortex of normal and diseased kidneys without superimposable staining for C5b-9 neoantigens. Cell remnants embedded in normal and sclerotic extracellular matrices expressed S protein antigen and also stained for C5b-9 neoantigens. Several lines of evidence suggested that S protein present in connective matrices most likely represents S protein or C5b-9 complexes trapped from the circulation. Glomerular immune deposits and arteriolar hyalin deposits which contained C5b-9 neoantigens also contained S protein antigen in the same location. In a few specimens from patients with membranous nephritis stage I and IgA nephropathy, immune deposits contained neither detectable C5b-9 neoantigens nor S protein. The observed strong co-staining of immune deposits for S-protein and C5b-9 caution against the generalization that C5b-9 within glomerular immune deposits represent membrane-bound cytolytic complement complexes.

Using anti-peroxidase Sheep IgG or their pepsic or papainic fragments intravenously injected to Wistar Munich normal Rats, the glomerular filtration barrier was localized at the lamina densa in ultrastructural studies. No evidence was found favoring the existence of a second barrier. The filtration barrier is absolute for the IgG but not for the pepsic and especially the papainic fragments which are reabsorbed by the proximal tubule.

Three patients with renal involvement, plasma cell dyscrasia and systemic light chain deposition are reported in whom well characterized amyloid deposits were also found in the vessel walls. This association, not yet reported, is probably more frequent than believed and still brings nearer these two manifestations of monoclonal light chain deposition. Whether or not the finding of amyloid deposits during systemic light chain deposition is a separate entity and modifies the prognosis remains to be answered.

This study demonstrates that human glomerular epithelial cells are able to bind heat aggregated immunoglobulins and antigen-antibody complexes. This has been observed on kidney cryostat sections, on whole glomeruli and on cultured visceral epithelial cells. Binding depends on the presence of the Fc portion of IgG and occurs in the absence of complement, showing that the IgG Fc receptor is different from the C3b receptor. The use of heat aggregated anti-peroxidase IgG and of peroxidase anti-peroxidase complexes allowed us to demonstrate, at the ultrastructural level, that the binding of the reagents at the plasma membrane was followed by their internalization within coated pits of vesicles. These observations strongly suggest that glomerular visceral epithelial cells are capable of receptor mediated endocytosis. The role of this process in glomerular diseases remains to be established.

Arteriovenous fistula (AVF) blood flow was evaluated in 32 dialysis patients using a pulsed Doppler velocimeter with two dominant features: a range-gated time system and a double transducer probe. With the proposed apparatus, the observation angle between the ultrasound beam and the vessel axis was known. In radial AVF, blood flow was 728 +/- 53 ml/min and was negatively correlated with the age of the AVF (r = -0.62; p less than 0.01). In brachial AVF, blood flow was 778 +/- 152 ml/min. In bovine heterograft AVF, blood flow was 1,225 +/- 125 ml/min. In the overall population, a negative relationship was observed between the diameter of the fistula and the blood flow velocity (r = -0.57; p less than 0.01). The study describes an accurate noninvasive method for the determination of fistula blood flow in dialysis patients, which may be helpful in the follow-up of the regional hemodynamics of this vascular access.

Nineteen Brown-Norway (BN) rats received intravenous injections of sheep anti-peroxidase (HRP) antibodies. Four BN rats were immunized to HRP. The anti-HRP antibodies were used to trace permeability pathways of large physiological molecules across different vessels of the small intestine. This organ was chosen because of the possibility of convenient "in situ" fixation and for the diversity of vessel types it contains. It was shown that: 1) There were no obvious transendothelial pathways in arteries with an elastic lamina. 2) The antibodies readily crossed fenestrated capillaries through the fenestrae. 3) There were two possible pathways through muscle capillaries and pericytic venules, namely transcytoplasmic vesicular "cactus-like" channels and interendothelial junctions. 4) Interendothelial permeability was a possible factor in veins with an elastic lamina. 5) Lymphatics were readily permeable through intercellular junctions and cytoplasmic vesicles.

A single injection either of isotonic or hypertonic saline solutions protected rats against acute renal failure (ARF) induced with glycerol. This protection was accompanied by increased urinary prostaglandin E (PGE) concentration. On the contrary, a single s.c. injection either of hypotonic saline or isotonic glucose solution, which did not increase urinary PGE concentration, or depletion of the endogenous catecholamines, using reserpine, did not protect the animals against acute renal failure.

The distribution of renin in two cases of segmental renal hypoplasia was investigated by immunofluorescence and the peroxidase anti-peroxidase (PAP) method using an anti-human renin antiserum. Renin-containing cells were found only in hypoplasic segments in the vicinity of altered glomeruli and small arteries. Well-preserved renal cortex and areas of chronic atrophic pyelonephritis failed to show any demonstrable site of renin production. Whatever is the mechanism of the disease, the characterization of large numbers of renin-containing cells in the affected kidney support a role for the renin-angiotensin system stimulation in this form of hypertension.

1. Highly specific antibodies to human renin were prepared in rabbits and used for the preparation of a renin-free substrate, the direct radioimmunoassay of renin in plasma and kidneys, and the localization of renin with fluoresceinated antibodies. 2. In a patient with a partially infarcted kidney, plasma renin activity was increased, and could be activated by acid. The direct measurement of plasma renin by radioimmunoassay gave identical values before and after acidification. 3. In the ischaemic part of the kidney, renin content was high, both by the enzymatic and the direct method of measurement. It was low in the non-ischaemic part of the kidney. 4. All afferent and some interlobular arteries of the obsolescent glomeruli were stained with fluoresceinated anti-renin antibodies. In the non-ischaemic area, the juxtaglomerular appratus did not stain. 5. Renin can now be measured in human plasma and kidney as an entity, by a specific radioimmunoassay. A direct investigation of this intrarenal hormone is now possible at the renal tissue level.

This review summarizes the main structural and biochemical features of the fibrillar constituents of the subendothelial layers of the arterial wall. Several constituents are directly identified by various histochemical methods and electron-microscopic studies. (1) The microfibrils (MF), stained by tannic acid, cationic stains such as ruthenium red, and various peroxidase-labeled lectins are mostly found in association with elastin within the internal elastic lamina (IEL). They have been characterized by chemical analysis as acidic glycoproteins, hydrolyzed by a variety of proteases, but resistant to collagenases. The endothelial cells seem to participate in their biosynthesis. (2) Elastin (El), which is the main constituent of the IEL, forms a wide, concentric, electron-lucent, tannic-acid-stainable zone. Fibrous El results from the association of tropoelastin (or proelastin) molecules by intermolecular cross-linkage. During the elastigenesis, this cross-linkage occurs directly between tropoelastin molecules which have been previously sterically oriented by the MF probably synthetized by the same cells (smooth muscle cells and possibly endothelial cells). (3) Interstitial collagen forms sparse fibers characterized by their cross-striation (with a periodicity of 640 A). They are relatively resistant to most proteolytic enzymes, except collagenases. They result from the intermolecular cross-linkage of rigid molecules, resulting themselves from the intramolecular cross-linkage of three helical alpha chains as a triple helix. The interstitial subendothelial collagen has been identified by indirect immunofluorescence as a type III collagen. The same technique has also been used to detect type IV collagen and fibronectin. This glycoprotein could play a role in the attachment of the endothelial cells to the fibrillar network of the subendothelium, despite an affinity which is greater toward denatured collagen than toward native collagen. One of the most important functions of the subendothelium is its role in thrombogenesis, in which both MF and collagen are involved. In type III collagen, this property is linked to the preservation of an ordered structure in which a 9-amino acids fragment, localized in the central part of each chain, could bear an adhesion site.

The light chain deposition disease was recently identified as a systemic clinicopathological entity characterized by amorphous extracellular deposits which differ from the amyloid substance. Various organs may be involved, notably the kidney, the liver, the myocardium and the skin. The histopathological aspects were investigated in 3 cases. By immunofluorescence using frozen sections the deposits were shown to contain monoclonal light kappa or lambda chains. By electron microscopy they appeared to be granular and usually located close to epithelial and/or vascular basal lamina. There was in every case a monoclonal lymphoplasmacytoid proliferation. In one case amyloid deposits were associated in small vessels. In another one, follow-up study after chemotherapy showed improvement of hepatomegaly, stabilization of renal function, and regression of light chain deposits in skin biopsy specimens.

In experiments in which blood was cross-circulating in rats, the blood pressure of the recipient dropped while that of the donor rose, following the increase of the circulating blood volume, produced by infusion either of saline or blood. The phenomenon was almost imperceptible when binephrectomized animals were used. In experiments in which the blood-bathed organ technique was used, prostaglandin-like substances were detected, released during the rise of the blood pressure, produced by the same stimulus (the expansion), in anaesthetized rats. A significant difference was found between the prostaglandin-like substances detected using the blood-bathed organ technique, in normal rats (5.387 ng per ml of blood plus or minus 0.288 = SEM) and those detected in binephrectomized rats (3.202 ng per ml of blood plus or minus 0.330, p smaller than 0.025). The biologically active substances detected in 25 ml of blood collected during expansion, while the assay organs showed a prostaglandin-like activity, were found to have the chromatographic behaviour and the bioassay properties of PGA, PGE and PGF series. A great quantity of the biologically active substances, having the chromatographic behaviour and the bioassay properties of PGA, PGS and PGF was detected in the rat renal medulla. Sufficient quantities of the released prostaglandin-like substances could escape the pulmonary vascular bed in this species of animal. It was concluded that a great quantity of the released prostaglandin-like substances came from the kidney and their release by this particular mechanism suggested that they play an important homeostatic role on the blood pressure, blood volume, and sodium and water balance regulation.

Fifteen renal biopsies from 13 transplanted patients with de novo membranous nephropathy (DNMN) were investigated by immunofluorescence for the presence of C5b-9 neoantigens of the terminal sequence of complement and for antigens expressed by C3 cleavage fragments. DNMN lesions were classified as stage I, II or III upon light and electron microscopy examination. Seven biopsies were classified as stage I DNMN and 8 stage II-III. All patients were proteinuric. In six biopsies with stage I DNMN, staining for C5b-9 neoantigens was restricted to a fine granular labeling in mesangial areas which was analogous to that seen in normal kidneys in contrast with extensive parietal labeling for IgG, C3d and factor H antigens. In eight biopsies with stage II-III DNMN, the pattern of staining with anti-C5b-9 neoantigens antibodies was similar to that obtained with anti-IgG, anti-C3d and anti-factor H antibodies. These results suggest that in situ activation of the whole complement sequence throughout C5b-9 only occurs on large immune deposits (stage II-III DNMN).