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Recent reports have suggested that there is a specific form of mesangial proliferative glomerulonephritis (GN) characterised by a diffuse and generalised mesangial deposition of IgM. The study included 149 consecutive patients with primary GN, who had adequate renal tissue for detailed light and immunofluorescent microscopy. Forty of these 149 patients had glomerular deposition of IgM. Of those 40, 20 had small and isolated focal deposits of IgM in sclerotic areas, but other immunoglobulins were predominant. The remaining 20 patients had IgM as the sole (16) or predominant (4) immunoglobulin deposited. Only one of these, however, fulfilled the published criteria of a mesangial proliferative GN with a diffuse and generalised mesangial deposition of IgM. The frequency of this entity in published series varies considerably, and there is a suspicion that in some studies patients with focal and segmental sclerosis and hyalinosis may have been included. More prospective studies are necessary to confirm whether there is a separate entity of IgM nephropathy.

Rabbit antibodies to human Tamm-Horsfall glycoprotein (prepared by salt precipitation from normal urine) were purified by affinity chromatography using columns containing Tamm-Horsfall glycoprotein linked to CNBr-activated Sepharose 4B. The specificity of these antibodies was determined by analysis of their binding characteristics on Western blots of Tamm-Horsfall protein from sodium dodecyl sulphate/polyacrylamide gradient gels and comparison with the reactivity of monoclonal antibodies to this glycoprotein. Optimal conditions of adsorption to poly(vinyl chloride) microtitre plates were established such that these purified antibodies could be used in a solid-phase radioimmunoassay for the determination of urinary Tamm-Horsfall-glycoprotein concentration. The specificity of the immunoassay was confirmed by competitive inhibition of the urinary Tamm-Horsfall glycoprotein by purified freeze-dried material in solution. A standard curve obtained with this material showed the radioimmunoassay to have a sensitivity of at least 5 ng/ml, with linearity between 30 and 600 ng/ml. The mean coefficient of variation over the linear section of the curve was 11.3 +/- 2.2% (n = 13). The effects of dialysis and freezing of urine samples before determination of Tamm-Horsfall-glycoprotein concentrations were investigated and the mean 24 h urinary excretion rate in 60 normal donors was shown to be 84.9 +/- 44.1 mg.

A method has been developed for the detection of C1q binding immune complexes in serum in which microculture plates are used as the solid-phase matrix for adsorption of C1q. This micromethod used only one-tenth of the amount of both C1q and [ 125 I]anti-human immunoglobulin per test and enabled 7 times as many samples to be tested in triplicate in comparison with the number performed in duplicate by the standard tube assay. 125 I-labelled C1q studies showed that adsorption varied with the brand of microplate used, some types of plate binding up to 66% of the labelled material. This is considerably more than that bound by the polystyrene tubes generally used for this assay. The increased capacity of the method allowed the binding to plates coated with the same batch of C1q to be assessed at various times after storage for 8–10 weeks at both 4°C and −70°C. A marked decrease in binding to C1q of aggregates of IgG was observed on storage for longer periods. Results with different batches of aggregated IgG which had been ultracentrifuged suggested that this may be used as an effective standard, stable on storage at −70°C. A comparison with the standard tube method of aggregated IgG, normal control sera and sera from patients with SLE showed that the micromethod adaptation of the C1q solid-phase binding radioimmunoassay is more economical and easier to perform and does not impair accuracy or standardization.

Sixty cases of colonic carcinoma have been investigated for antitumour immunoreactivity. The tests employed were blood lymphocyte reactivity and complement-dependent serum cytotoxicity against cultured tumour cells, and immunofluorescence for membrane staining of viable tumour cells and cytoplasmic staining of dried tumour cells in films. Nineteen cases were positive by one or more tests and the most frequent positive response, lymphocytotoxicity, was detected in 8 of the 24 cases tested in this way. The lymphocytotoxicity persisted in a case tested three times over a year. Immunoreactivity against tumour cell surface, as by lymphocyte or serum cytotoxicity or membrane immunofluorescence, was restricted to colonic carcinomas but there was an additional element of individual specificity; cross-reactivity with other tissues and tumours was not observed. Lymphocytes from regional lymph nodes were non-reactive even in a case with positive blood lymphocyte cytotoxicity against the carcinoma cells.

Two young men with anti-glomerular basement membrane (anti-GBM) antibody-induced Goodpasture's syndrome are described. Despite the characteristic renal morphological features and high titers of anti-GBM antibody, they had normal renal function. Both patients recovered spontaneously without treatment and remain well with normal renal function more than four years after presentation. The use of more sensitive diagnostic techniques has demonstrated that there is a broad spectrum of clinical severity in this disease and that mild cases can be expected to have a good outcome.

Glomerular basement membranes showed strong silver labelling on electron microscopy in NZB/NZW mice fed 12 mmol AgNO3 for 6 weeks at ages from 1-7 months. Although some silver granules were seen within mesangial immune deposits following their concurrent deposition, silver was usually deposited in electron-lucent areas around pre-existing deposits, or formed a boundary to an expanded mesangium when immune deposits subsequently developed. Immune deposits in capillary loops occurred on the outer or inner aspect of the zone of silver labelling.

Tamm-Horsfall glycoprotein (TH) distribution was studied using a biotin-avidin immunoperoxidase technique in renal biopsies from 166 consecutive patients and 8 normal kidneys. Tubulointerstitial damage was independently assessed and graded. In 109 patients TH antibodies were measured by ELISA and in 30 of these urinary TH and beta 2-microglobulin excretions were measured by radioimmunoassay. In 124 biopsies only distal tubular epithelium and casts were stained. Glomerular space (8) or interstitial (34) deposits were seen in 42 biopsies; 16/68 with glomerulonephritis, 4/14 with systemic vasculitis, 12/33 with chronic interstitial nephritis, 1/8 with acute interstitial nephritis, 9/43 with other nephropathies. There was no correlation between TH distribution and the degree of tubulointerstitial damage (p greater than 0.5), urinary TH excretion (p greater than 0.05), urinary beta 2-microglobulin excretion (p greater than 0.05), glomerular filtration rate, urinary concentrating ability, or the incidence of pyuria. TH antibodies did not correlate with TH distribution (p greater than 0.5) or the degree of tubulointerstitial damage. Abnormal TH distribution showed no statistical relationship to the degree of tubulointerstitial damage, changes in renal function or levels of TH antibodies.

Tamm-Horsfall urinary glycoprotein (THP), prepared by salt precipitation of pooled urine from normal individuals, stimulated purified human peripheral blood lymphocytes (PBL) to undergo blastoid transformation. the response was measured by tritiated thymidine uptake into DNA after 6 days in culture. Several batches of THP stimulated, in varying degrees, all samples of PBL tested and the response approached that seen with the mitogens phytohaemagglutinin (PHA), Concanavalin A (Con A) and pokeweed mitogen (PWM) after 4 days in culture. The response usually exceeded that seen after 6 days with tuberculin purified protein derivative (PPD) in Mantoux positive lymphocyte donors.

The ultrastructural localization of Tamm-Horsfall protein (THP) was studied in paraformaldehyde-fixed human renal biopsies. Pre-embedding and post-embedding immunogold labelling techniques were developed utilizing a monoclonal antibody specific for human urinary THP. With the pre-embedding technique, membrane contrast was enhanced by osmification thus allowing precise localization of gold particles. Reasonable tissue penetration of antibodies was achieved without compromising ultrastructural detail. The hydrophilic resin LR White was used for post-embedding labelling to ensure maximum penetration of antibodies. However, sections had only mild osmification and consequently localization of label was less certain. Both labelling techniques gave similar results. THP was found to be associated with two renal cell types. Epithelial cells lining the thick ascending limb of Henle's loop had gold label closely associated with the whole cell plasmalemma, with some of these cells having an apparently random distribution of label throughout the cytoplasm. Only the luminal plasmalemma of epithelial cells lining distal convoluted tubules were found to be labelled. Basolateral membranes and the cytoplasm of these cells were negative. The use of a monoclonal antibody of defined specificity combined with the two immunolabelling procedures represents a precise reliable method for studying ultrastructural localization of THP in the human kidney.

A method is described for the culture of isolated intact mouse glomeruli. Cultures showed adherent glomeruli after 2 days and from 2-4 days a monolayer of cells began to develop around the points of adherence. The predominant cell (Type I) was 80-200 micrometer in diameter with cytoplasmic extensions, later becoming polyhedral and often multinucleated. Type II spindle cells, 70-100 micrometer in length, were less prominent in the earlier stages and later formed sheaves between Type I cells. Small phagocytic Type III cells, 10-20 micrometer in diameter, were not prominent in cultures from normal kidneys and tended to form small clusters on top of the Type I cell monolayer.

Tamm-Horsfall protein was detected within the capsular space by immunofluorescence in 7 of 72 consecutive patients on whom renal immunopathological studies were performed. Three patients showed prominent aggregates or crescentic collections affecting 30-50% glomeruli; the remaining four patients showed smaller aggregates between lobules. All patients showed pathological evidence of tubulointerstitial disease. It is suggested that Tamm-Horsfall protein in the capsular space is a sign of intratubular urinary backflow and that Tamm-Horsfall antiserum is a useful addition to the reagents used in the immunofluorescence study of renal biopsies.

Three cases are presented of a recently defined group of patients with renal disease who presented with macroscopic or persisted microscopic haematuria. These patients were found to have deposition of IgA in the glomerulus. They may thus be classified as suffering from an immunologically related glomerulonephritis.

Comparative studies of glomerular cultures from NZB/W and normal control mice aged 2, 4, 6, 8, 10 and 12 months revealed a significant increase in the number of phagocytic cells in cultures from NZB/W mice at all ages. These cells on electron microscopy had the appearance of macrophages and on immunofluorescence showed Fc receptors and reacted with rabbit anti-mouse macrophage serum. The cells appear to be of blood monocyte origin and it is likely that they play a role in the pathogenesis in NZB/W mice of the glomerulopathy associated with clearance of immune complexes.

A rabbiter who was repeatedly exposed to sodium monofluoroacetate (compound 1080) developed renal failure and evidence of other organ damage. This is believed to be the first report of chronic sodium monofluoroacetate intoxication occurring in man.

Immunofluorescence tests on 94 human sera reacting with rat gastric parietal cells revealed that 41 (44%) of the sera contained antibody to a rat parietal cell antigen that was distinct from the pernicious anaemia autoantigen. Ten of the sera contained antibodies to both parietal cell antigens. The remaining 53 (56%) sera contained only parietal cell antibodies of the pernicious anaemia type. We recommend that mouse gastric mucosa, which does not react with the heterologous rat parietal cell antibody, replace rat gastric mucosa for immunofluorescence diagnostic tests.

After the age of 6 months, NZB/NZW mice develop almost 100% incidence of serum antinuclear factor (ANF) which is located in the IgG immunoglobulin fraction, binds guinea-pig complement and gives homogeneous, membranous and speckled immunofluorescent nuclear staining patterns. No specific in vitro cytotoxic activity against homologous kidney cells was detected in serum from these mice, but their lymphoid cells clustered around a proportion of kidney cells which subsequently degenerated.

The immunofluorescent staining characteristics of antibodies against rat and mouse kidney tubule brush border, produced in rabbits immunized with microsomal or mitochondrial fractions of rat kidney, were compared with those of human antibodies against mitochondria obtained from patients with biliary cirrhosis. With the rabbit antisera, brush border staining was confined to the epithelium of the proximal renal tubules while the human antimitochondrial sera stained proximal and distal tubules. Absorptions with a mitochondrial fraction prepared from rat liver inhibited the human serum activity but had no effect on brush border activity in the rabbit serum which was inhibited only by the rat kidney subcellular fractions.

RAT colon antigens have been used for haemagglutination and immunofluorescence tests in serological investigations of ulcerative colitis patients1,2. As part of the reaction with the rat colon may be caused by a blood group A-like substance3, absorption of the sera with human group A1 red cells can reduce the capacity for immunofluorescent staining or haemagglutination, but in many cases significant activity remains. We have examined sera from normal people without a personal history of colonic disease and have detected, even after A cell absorption, some which give strong immunofluorescent staining and several with high haemagglutination titres.

Bacteriocin activity can be detected and assayed by a modification of the punchhole method.

SUMMARY Studies of the heat stability of a human antibody against thyroglobulin showed that after heating at 70° for 10 min. its potency was reduced to 2% of the initial value. Similarly, the potency of a preparation of long-acting thyroid stimulator (LATS) was reduced to significantly less than 10% by this treatment, whereas the potency of a human thyroid-stimulating hormone (TSH) preparation was reduced only to 45%, with a lower fiducial limit of 26% for P = 0·05. It is concluded that LATS is less stable to heat than is TSH. LATS did not differ from the antibody in heat stability.

Cardiac myofiber band antibodies, cross-reactive with skeletal muscle cross-striations and with the cytoplasm of thymic myoid cells, were demonstrated in sera from patients with acute rheumatlc fever and uncomplicated group A streptococcal infections.