In vitro culture of the proximal tubule of the bovine nephron : the fate of the histiospecific antigens and neosynthesis of an alpha-foetoprotein

The isolation of pure tubules of the outer cortex of the foetal bovine kidney, using a previously described methods, has shown that the tubule suspension obtained is almost entirely constituted of proximal tubule fragments. The proximal cells obtained from this suspension were grown in vitro. The previously called "nephrospecific" antigens NS1-2 were shown to be strictly specific for the cells of the proximal tubule, which is an "histion" of the kidney, that is to say an ultimate unit of differentiation of this organ. The fate of these antigens, henceforth termed "histiospecific antigens" (of the proximal tubule), was followed in primary monolayer cultures of the proximal tubules, using immunodiffusion tests and immunofluorescence. A rapid decrease in this antigen content of the cells was observed during the in vitro culture. An immunoautoradiographic study demonstrated that the synthesis of these antigens was switched off in the confluent cultures. A similar autoradiographic study demonstrated that these same proximal cells at confluence synthesized a bovine alpha1-foetoprotein, which had been detected in earlier studies of kidney cortex cultures. This double antigenic shift is correlated with the in vitro evolution of some morphological markers of the proximal cells, as studied with the transmission and the scanning electron microscope. The factors responsible for these results are discussed.

Experimental glomerulonephritis in the rat induced by antibodies directed against tubular antigens. I. The natural history: a histologic and immunohistologic study at the light microscopic and the ultrastructural level

A new form of experimental immune complex glomerulonephritis is described which is induced by one single injection of heterologous antibody directed against antigens present in the brush border of the proximal tubules of the rat kidney. In this model, antigen-antibody complexes are deposited as early as 3 hours after injection of the heterologous antiserum. The first localization of these complexes is seen in the dense layer of the glomerular basement membrane. Later, they move up to the lamina rara externa and stay there for at least 3 months. This model is easily reproducible and offers possibilities for studying the effects of medication on the deposition of immune complexes.

Determinants of glomerular filtration in experimental glomerulonephritis in the rat

Pressures and flows were measured in surface glomerular capillaries, efferent arterioles, and proximal tubules of 22 Wistar rats in the early autologous phase of nephrotoxic serum nephritis (NSN). Linear deposits of rabbit and rat IgG and C3 component of complement were demonstrated in glomerular capillary walls by immunofluorescence microscopy. Light microscopy revealed diffuse proliferative glomerulonephritis, and proteinuria was present. Although whole kidney and single nephron glomerular filtration rate (GFR) in NSN (0.8 plus or minus 0.04 SE2 ml/min and 2 plus or minus 2 nl/min, respectively) remained unchanged from values in 16 weight-matched NORMAL HYDROPENIC control rats (0.8 plus or minus 0.08 and 28 plus or minus 2), important alterations in glomerular dynamics were noted. Mean transcapillary hydraulic pressure difference (deltaP) averaged 41 plus or minus 1 mm Hg in NSN versus 32 plus or minus 1 in controls (P LESS THAN 0.005). Oncotic pressures at the afferent (piA) end of the glomerular capillary were similar in both groups ( 16 mm /g) but increased much less by the efferent end (piE) in NSN (to 29 plus or minus 1 mm Hg) than in controls (33 plus or minus 1, P less than 0.025). Hence, equality between deltaP and piE, denoting filtration pressure equilibrium, obtained in control but not in NSN rats. While glomerular plasma flow rate was slightly higher in NSN (88 plus or minus 8 nl/min) than in controls (76 plus or minus 6, P greater than 0.2), the failure to achieve filtration equilibrium in NSN rats was primarily the consequence of a marked fall in the glomerular capillary ultrafiltration coefficient, Kf, to a mean value of 0.03 nl/(s times mm Hg), considerably lower than that found recently for the normal rat, 0.08 nl/(s times mm Hg). Thus, despite extensive glomerular injury, evidenced morphologically and by the low Kf, GFR remained normal. This maintenance of GFR resulted primarily from increases in deltaP, which tended to increase the net driving force for filtration, and thereby compensate for the reduction in Kf.

Increased immunologic reactivity between human glomerular basement membrane and group A type 12 streptococcal cell membrane after carbohydrase treatment

Anti-streptococcal cell membrane and anti-human glomerular antisera were evaluated on normal human kidney sections by an indirect immunofluorescent test both before and after absorptions with homologous and heterologous membrane preparations. The observed cross-reactions were potentiated by removal of carbohydrate units from both membrane-types by carbohydrase, a mixture of carbohydrate-cleaving enzymes.

Studies on heterophile antibodies in transplantation sera

By means of double diffusion in gel reactions, "heterophile" antibodies were demonstrated in human renal transplantation sera. Of thirty-two recipients of renal allografts, 12 (37 per cent) had antibodies to extract of bovine erythrocyte stromata, and 5 (19 per cent) of 26 recipients produced antibodies to extract of sheep erythrocyte stromata. These antibodies became detectable 1-6 months after transplantation and persisted for several months or years. However, the strength of reactions given by individual serum samples from the same recipient varied considerably. Sera from the same recipient gave a reaction of identify, while sera from two different recipients frequently gave reactions of partial identity or nonidentity. The antibodies reacting with bovine stroma extract were distinct from those reacting with sheep stroma extract. Evidence was also presented that the heterophile antibodies in transplantation sera are different from Paul-Bunnell antibodies in infectious mononucleosis sera. Some of the HL-A typing sera were shown to contain antibodies against bovine stroma extract. The antigen recognized by these sera in the bovine stroma extract was not related to any HL-A specificity. Three of eight rabbits which received skin and renal allografts formed antibodies against bovine stroma extract. Absorption studies clearly demonstrated that these antibodies are directed against antigens present in the donor's, but not in the recipient's tissues.

Human smooth muscle autoantibody. Its identification as antiactin antibody and a study of its binding to "nonmuscular" cells

When human serum containing smooth muscle autoantibodies (SMA) is incubated with extracts containing thrombosthenin (the contractile material of platelets) or thrombosthenin-A (the actin-like moiety of thrombosthenin), it loses its ability to bind to smooth muscle. Such binding is also diminished when SMA serum is incubated with lysed platelets; this effect is not seen if the SMA serum is incubated with intact platelets. The incubation of other autoantibodies (such as antimitochondrial or antinuclear antibodies) with thrombosthenin does not affect their binding to the specific antigens. It appears that SMA is directed against the actin fraction of thrombosthenin-ie, SMA is an antiactin antibody. Hence the name of antiactin autoantibody (AAA) seems more appropriate than smooth muscle autoantibody (SMA). A study of the distribution of antiactin autoantibody binding in rat, rabbit and man shows that several "nonmuscular" structures contain actin under normal conditions; these include megakaryocytes and platelets, normal rat hepatocytes, the brush borders of renal tubules, the periphery of epithelial cells of the intestine, polymorphs and lymphocytes in lymph nodes (but not thymic cortical lymphocytes). In addition, certain cell types (such as granulation tissue fibroblasts, cultivated fibroblasts, hepatocytes or regenerating liver and epidermal cells growing over a skin wound) can reversibly acquire a massive network of actin-containing microfilaments resembling those in smooth muscle.

Systemic lupus erythematosus. Studies of the antibodies bound to skin

Systemic lupus erythematosus is characterized by antibodies demonstrable by immunofluorescence on the renal glomeruli and at the basement membrane area of both normal and involved skin. Acid eluates from glomeruli and from normal-appearing skin of three patients with systemic lupus erythematosus contained an antinuclear antibody. This antibody fixes complement and produces a mixed immunofluorescent pattern. Anti-deoxyribonucleic acid or antiextractable nuclear antigen antibodies may be present. This antibody is concentrated on the skin and glomerular basement membrane in proportion to the total serum IgG concentration. In two cases the skin eluate contains, in addition to the antinuclear antibody, a basement membrane antibody that fixes complement, gives a linear immunofluorescent pattern, and appears to be similar (although not identical) to the pemphigoid antibody.

Antibody enzyme conjugates: the preparation of intermolecular conjugates of horseradish peroxidase and antibody and their use in immunohistology of renal cortex

The studies reported were done with the objectives of preparing several different peroxidase-labeled antibody conjugates and of testing their usefulness for the detection of soluble and insoluble tissue antigens. Glutaraldehyde, toluene diisocyanate and N,N'-dicyclohexyl carbodiimide were used to cross-link horseradish peroxidase to goat anti-rabbit immunoglobulin G; the resulting conjugates were characterized by molecular size and enzymatic and immunologic activity. They were then tested for their properties as immunohistologic reagents using 0.5-µ sections of freeze-substituted paraffin-embedded renal cortical tissue. Excellent results were obtained with a highly polymerized conjugate made with glutaraldehyde and with an unpolymerized conjugate made with toluene diisocyanate. With the use of these conjugates tissue localization of both soluble and insoluble antigens was achieved after subsequent fixation of tissue and counterstaining with periodic acid-Schiff-hematoxylin.