Passive Heymann nephritis (PHN) is a model of human membranous nephropathy that is characterized by formation of granular subepithelial immune deposits in the glomerular capillary wall which results in complement activation. This is causally related to damage of the filtration barrier and subsequent proteinuria. The local accumulation of injurious reactive oxygen species (ROS) is a major effector mechanism in PHN. ROS may induce tissue damage by initiating lipid peroxidation (LPO). In turn, this leads to adduct formation between breakdown products of LPO with structural proteins, such as formation of malondialdehyde (MDA) or 4-hydroxynonenal-lysine adducts. To examine the role of LPO in the development of proteinuria we have localized MDA and 4-hydroxynoneal-lysine adducts in glomeruli of PHN rats by immunofluoresence microscopy, using specific monoclonal antibodies. By immunogold electron microscopy, MDA adducts were localized to cytoplasmic vesicles and cell membranes of glomerular epithelial cells, to the glomerular basement membrane (GBM), and also to immune deposits. Type IV collagen was specifically identified as being modified by MDA adducts, using a variety of techniques. Collagenase pretreatment of GBM extracts indicated that the NC-1 domain of type IV collagen was a site of adduct formation. When LPO was inhibited by pretreatment of PHN rats with the antioxidant probucol, proteinuria was reduced by -85%, and glomerular immunostaining for dialdehyde adducts was markedly reduced, even though the formation of immune deposits was not affected. By contrast, lowering of the serum cholesterol levels had no influence on the development of proteinuria.These findings are consistent with the premise that ROSinduced glomerular injury in PHN involves LPO and that this results not only in damage of cell membranes but in modification of type IV collagen in the GBM as well. The close temporal correlation of the occurrence of LPO with

A B S T R A C T Macrophages were shown by the use of glomerular cell culture and morphologic techniques to be present in large numbers within the glomeruli of rabbits with acute serum sickness (AcSS) and in a passive model of the autologous phase of antiglomerular basement membrane (GBM) antibodyinduced glomerulonephritis (PAGBMN). To determine the part played by these cells in the glomerular injury, animals were treated with a sheep anti-rabbit macrophage serum (AMS) or normal sheep serum (NSS). NSS administration had no effect on the development of either model of glomerulonephritis. The use of AMS reduced the number of circulating monocytes and prevented the accumulation of macrophages within glomeruli in both models (AcSS/NSS, mean 126/glomerulus, range 40-251; AcSS/AMS, mean 8, range 1-44; PAGBMN/NSS, mean 52, range 27-69; PAGBMN/AMS, mean 5, range 2-7). The AMS-treated rabbits had only minor histologic lesion and profound reduction in proteinuria (AcSS/NSS, mean 516 mg/24 h, range 200-991; AcSS/AMS, mean 41, range 3-161; PAGBMN/NSS, mean 335, range 55-975; PAGBMN/AMS, mean 10, range 2-24). Similar studies in the heterologous phase of glomerular injury induced by the same anti-GBM antibody revealed no effect of the AMS on this polymorpho-

Reactive oxygen species (ROS) have been implicated in the production of glomerular damage in passive Heymann nephritis (PHN), an experimental form of membranous nephropathy with neutrophil-independent proteinuria. Immunohistochemistry with monoclonal antibodies specific for cytochrome b558 (a major component of the oxidoreductase complex of the respiratory burst in stimulated neutrophilic granulocytes) showed that this enzyme is localized within visceral glomerular epithelial cells (GECs) in a dense, granular pattern in rats with PHN and proteinuria. By immunoelectron-microscopy, the cytochrome was found in membrane vesicles within the GEC and also extraceliularly on the GEC membranes facing the glomerular basement membrane (GBM). By immunoblotting, cytochrome bsm was detected in highest concentration in lysates of isolated glomeruli from proteinuric rats. By contrast, only traces were found in normal glomeruli by immunohistochemistry. Depletion of complement abolished the expression of the cytochrome. Using an ultrastructural cerium-H202 histochemistry technique, the functional activity of the glomerular ROS-generating system was demonstrated exclusively in proteinuric PHN, where H202 was found in highest concentration within the GBM. These results provide evidence that in rats with PHN and proteinuria, the GECs express and externalize respiratory-burst enzymes that generate ROS in a manner similar to neutrophilic granulocytes, which could then lead to glomerular damage.Passive Heymann nephritis (PHN) is an experimental model of human membranous nephropathy that is induced in rats by injection of antibodies directed against crude fractions of kidney cortex (Fx1A) (1). There is evidence that the subepithelial immune deposits in PHN are formed in situ from immune complexes of the membrane glycoprotein (gp) complex gp330/44 kDa, which is present in glomerular visceral epithelial cells (GEC) and from circulating antibody (2-4).

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SummaryRenal injury in diabetes mellitus is associated with progressive interstitial fibrosis and extracellular matrix accumulation. However, the phenotypes of cells forming the interstitial infiltrate in diabetic nephropathy have not been precisely defined. There is increasing evidence for the association of mast cells with angiogenesis, chronic inflammatory conditions and fibrosis. We have recently shown that human mast cells can produce the non-fibrillar short chain type VIII collagen in vivo. Using immunohistochemistry, in situ hybridisation and reverse transcriptasepolymerase chain reaction, we examined the contribution of mast cells and type VIII collagen to the fibrotic changes occurring in biopsy-proven diabetic nephropathy. We observed that the number of interstitial mast cells was significantly increased in diabetic nephropathy compared with normal kidney tissue. In specimens from diabetic subjects, intense immunohistochemical staining for type VIII collagen was detected in mast cells, on periglomerular fibres and in perivascular and interstitial sites. The expression of type VIII collagen in periglomerular and interstitial sites coincided with that of alpha smooth muscle actin, a marker for myofibroblastic differentiation, mRNA for type VIII collagen was detected by reverse transcriptase-polymerase chain reaction in diabetic nephropathy and in a human mast cell line. By in situ hybridisation the transcripts for type VIII collagen were localised to renal mast cells. The increased number of mast cells and the elevated type VIII collagen deposition in human diabetic nephropathy provides a potential link between the extracellular matrix accumulation and the fibrosis observed in this condition. [Diabetologia (1996[Diabetologia ( ) 39: 1215[Diabetologia ( -1222

Human infection with Rhodococcus equi is apparently rare with most published reports describing the development of lung abscesses in immunocompromised hosts. Of only 18 cases of infection previously recorded, four have recently occurred in patients with the acquired immune deficiency syndrome (AIDS). In Australasia, R. equi has frequently been isolated from soil and infected farm animals yet no human infections have been reported thus far. Three cases of R. equi infection have occurred in New Zealand and, collectively, they cover a wider spectrum of disease than that previously recognised. The natural history of R. equi infections, their clinical features and treatment are described in the light of our recent experience.

Macrophage accumulation is a feature of some aggressive forms of human and experimental glomerulonephritis (GN). Both antibody Fc components and T cells may cause macrophage accumulation; however, there has been no previous demonstration of T cells at the site of injury in GN, although some indirect evidence of their possible participation has been reported. Specific monoclonal anti-rat T lymphocyte antibodies W3/13, W3/25, and Ox8 were used to demonstrate T cells within the glomeruli of rats with an augmented autologous anti-GBM GN, by indirect immunofluorescence. The injury in this model has been shown to be mediated by macrophages. The T cell infiltrate consisted mainly of T helper cells, was maximal 24 hr after induction of the disease and clearly preceded the peak influx of macrophages and glomerular damage. Suppression of T cell function using cyclosporin prevented T cell accumulation and the subsequent macrophage-induced injury. Glomerular T cells were not seen in passively induced GN. These studies support a role for cell-mediated immunity in attracting macrophages and initiating injury in experimental anti-GBM antibody-induced GN.

Exercise capacity is documented to be poor in patients with end stage renal failure undergoing regular hemodialysis, but there is little information about exercise capacity in patients on continuous ambulatory peritoneal dialysis (CAPD). We studied a group of 18 patients undergoing CAPD, with a variety of cardiorespiratory disorders, using a progressive load treadmill exercise test. The influence of intraperitoneal fluid on work capacity was also assessed. The mean maximum oxygen uptake (VO2max) of the CAPD patients was reduced considerably (14.6 ml kg-1 min-1) compared with matched control subjects (33.6 ml kg-1 min-1). This corresponded to the difficulty experienced by these patients in carrying out daily activities. There was no significant change in VO2max or in maximum heart rate with the peritoneal cavity full. We conclude that physical fitness is poor in CAPD patients and that the infusion of dialysis fluid into the peritoneal cavity does not affect physical work capacity further.